System and method for blockchain-based notification

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for blockchain-based notification are provided. One of the methods includes: obtaining, from a computing device associated with a first decentralized identifier (DID), a query about event data; in response to the obtained query, searching a data store to obtain one or more notifications for event data associated with a second DID, wherein a DID document associated with the second DID comprises the first DID, and wherein the DID document is stored in a blockchain; and providing the one or more notifications for the computing device associated with the first DID.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of InternationalPatent Application No. PCT/CN2019/103730, filed on Aug. 30, 2019, andentitled “SYSTEM AND METHOD FOR BLOCKCHAIN-BASED NOTIFICATION”, whichclaims priority to and benefits of International Application No.PCT/CN2019/095299 filed with the China National Intellectual PropertyAdministration (CNIPA) on Jul. 9, 2019, International Application No.PCT/CN2019/095303 filed with the CNIPA on Jul. 9, 2019, andInternational Application No. PCT/CN2019/094396, filed with the CNIPA onJul. 2, 2019. International Application No. PCT/CN2019/095299 andInternational Application No. PCT/CN2019/095303 also claim priority toand benefits of International Application No. PCT/CN2019/094396. Theentire contents of all of the above-identified applications areincorporated herein by reference.

TECHNICAL FIELD

This application generally relates to methods and devices forblockchain-based notification.

BACKGROUND

Traditional identity management systems are based on centralizedauthorities such as corporate directory services, certificateauthorities, or domain name registries. Each of the centralizedauthorities may serve as a root of trust that provides credibility tothe identity it endorses. For such systems, data associated with theidentities is often stored in centralized databases, if not traditionalinformation storage media. The maintenance of identity of each person orentity is under the control of the centralized authorities. Given itsnature, traditional identity management systems are subject to securityrisks suffered by each of the centralized authorities and provideinefficient mechanisms for the aggregation of identities or credentialsprovided by different centralized authorities. In such systems,individual entities or identity owners are often neither free to choosethe root of trust nor in control over their own identities orcredentials. Authentication and verification of their identities foractivities such as receiving notifications often prove to beinefficient.

Blockchain technology provides an opportunity to establish a trustworthydecentralized system that does not require trust in each member of thesystem. Blockchain provides data storage in a decentralized fashion bykeeping the data in a series of data blocks having precedencerelationship between each other. The chain of blocks is maintained andupdated by a network of blockchain nodes, which are also responsible forvalidating data under a consensus scheme. The stored data may includemany data types, such as financial transactions among parties,historical access information, etc.

Many blockchains (e.g., the Ethereum blockchain) have enabled blockchaincontracts (also referred to as smart contracts) that are executedthrough blockchain transactions. Blockchain transactions are signedmessages originated by externally owned accounts (e.g., blockchainaccounts), transmitted by the blockchain network, and recorded in theblockchain. The blockchain contracts may be written to achieve variousfunctions, such as adding data to blockchain accounts, changing data inthe blockchain, etc. Thus, the blockchain can be maintained and updatedby executing various blockchain transactions.

Blockchain technology provides the means for managing a root of trustwithout centralized authority. However, identity management systemsbuilt based on blockchain often present substantive technical barriersfor average users by requiring storage of a blockchain ledger,capabilities to create and execute blockchain transactions andcontracts, or participation in the consensus scheme of the blockchain.Such identity management systems also likely require frequent access toand interaction with the blockchain network, which may be costly andresource consuming. For business entities with the needs to manageidentities for a large number of users, such identity management systemsoften prove to be inefficient and user-unfriendly. Mapping betweenidentities managed by such an identity management system and accounts orservice IDs kept by business entities are often difficult to maintain.Finally, the identity management systems may often allow anonymous andarbitrary creation of decentralized identities and provide little meansto authenticate the real-world identities of the individuals behind thedecentralized identities.

SUMMARY

Various embodiments of the specification include, but are not limitedto, systems, methods, and non-transitory computer readable media forblockchain-based notification.

According to some embodiments, a computer-implemented method forblockchain-based notification comprises: obtaining, from a computingdevice associated with a first decentralized identifier (DID), a queryabout event data; in response to the obtained query, searching a datastore to obtain one or more notifications for event data associated witha second DID, wherein a DID document associated with the second DIDcomprises the first DID, and wherein the DID document is stored in ablockchain; and providing the one or more notifications for thecomputing device associated with the first DID.

In some embodiments, the DID document comprises a parameter indicating acreator of the second DID; and the parameter comprises the first DID.

In some embodiments, the DID document comprises a parameter indicating acontroller of the second DID; and the parameter comprises the first DID.

In some embodiments, the event data is associated with a verifiableclaim; and a representation of the verifiable claim is stored in theblockchain.

In some embodiments, the event data associated with the second DIDcomprises one or more of the following: a registration of the second DIDin the blockchain; an update to the DID document in the blockchain; anissuance of a first verifiable claim associated with the second DID,wherein the second DID corresponds to an issuer of the first verifiableclaim; and an issuance of a second verifiable claim associated with thesecond DID, wherein the second DID corresponds to a subject of thesecond verifiable claim.

In some embodiments, before obtaining the query, the method furthercomprises: obtaining a plurality of notifications from one or moremessage queues; and storing the plurality of notifications in the datastore in association with information of corresponding DIDs andcorresponding blockchain heights in the blockchain, wherein theplurality of notifications comprise the one or more notifications forthe event data associated with the second DID.

In some embodiments, after obtaining the plurality of notifications, themethod further comprises: filtering the plurality of notifications toremove one or more unauthorized notifications.

In some embodiments, after obtaining the plurality of notifications, themethod further comprises: categorizing the plurality of notificationsbased on one or more of the following notification parameters: eventtype, DID, DID creator, DID controller, notification recipient,verifiable claim issuer, and verifiable claim subject.

In some embodiments, searching the data store to obtain the one or morenotifications for the event data associated with the second DIDcomprises: searching the data store based on a current starting heightof the blockchain to obtain the one or more notifications for the eventdata associated with the second DID.

In some embodiments, searching the data store based on the currentstarting height of the blockchain to obtain the one or morenotifications for the event data associated with the second DIDcomprises: searching from the current starting height of the blockchainto a current ending height of the blockchain for the one or morenotifications associated with the event data; and the method furthercomprises providing the current ending height of the blockchain for oneor more of the following: the computing device associated with the firstDID and another computing device associated with the second DID.

In some embodiments, the query comprises the current starting height ofthe blockchain; and the current starting height of the blockchaincomprises an offset from a previous ending height of the blockchain of aprevious search.

In some embodiments, the query comprises the current starting height ofthe blockchain; and the current starting height of the blockchain is aprevious ending height of the blockchain of a previous search.

According to other embodiments, a system for blockchain-basednotification comprises one or more processors and one or morecomputer-readable memories coupled to the one or more processors andhaving instructions stored thereon that are executable by the one ormore processors to perform the method of any of the precedingembodiments.

According to yet other embodiments, a non-transitory computer-readablestorage medium is configured with instructions executable by one or moreprocessors to cause the one or more processors to perform the method ofany of the preceding embodiments.

According to still other embodiments, an apparatus for blockchain-basednotification comprises a plurality of modules for performing the methodof any of the preceding embodiments.

According to some embodiments, a system for blockchain-basednotification comprises one or more processors and one or morecomputer-readable memories coupled to the one or more processors andhaving instructions stored thereon that are executable by the one ormore processors to perform operations comprising: obtaining, from acomputing device associated with a first decentralized identifier (DID),a query about event data; in response to the obtained query, searching adata store to obtain one or more notifications for event data associatedwith a second DID, wherein a DID document associated with the second DIDcomprises the first DID, and wherein the DID document is stored in ablockchain; and providing the one or more notifications for thecomputing device associated with the first DID.

According to other embodiments, a non-transitory computer-readablestorage medium is configured with instructions executable by one or moreprocessors to cause the one or more processors to perform operationscomprising: obtaining, from a computing device associated with a firstdecentralized identifier (DID), a query about event data; in response tothe obtained query, searching a data store to obtain one or morenotifications for event data associated with a second DID, wherein a DIDdocument associated with the second DID comprises the first DID, andwherein the DID document is stored in a blockchain; and providing theone or more notifications for the computing device associated with thefirst DID.

According to yet other embodiments, an apparatus for blockchain-basednotification comprises an obtaining module for obtaining, from acomputing device associated with a first decentralized identifier (DID),a query about event data; a searching module for, in response to theobtained query, searching a data store to obtain one or morenotifications for event data associated with a second DID, wherein a DIDdocument associated with the second DID comprises the first DID, andwherein the DID document is stored in a blockchain; and a providingmodule for providing the one or more notifications for the computingdevice associated with the first DID.

Embodiments disclosed herein have one or more technical effects. In someembodiments, one or more parameters may be added to a DID documentassociated with a DID to indicate creators, controllers, or otherentities authorized to receive notifications related to the DID's ownerfrom a messenger. Thus, authorized recipients for notifications of eventdata associated with the DID can be conveniently determined based on theDID document and securely stored in the blockchain. In one embodiment,this provides convenience to the DID's owner by obviating the need forequipment commitment, specialized knowledge acquisition, blockchainquery, notification retrieval, identity credentials (e.g., cryptographickeys) maintenance, etc. In one embodiment, for entities with the needsto manage identities for a large number of users, the entities maycentralize interactions with the blockchain network to obtainnotifications for the users. In one embodiment, the messenger mayobtain, filter, and categorize notifications from the blockchain forswift and accurate delivery to various entities. In one embodiment,information security is ensured because the one or more parameters inthe DID document set forth the authorized recipients of thenotifications related to the DID's owner. Thus, the DID's owner'sprivacy is protected by configuring the parameters in the DID document.In some embodiments, consistency and flexibility for notificationdelivery is ensured by allowing the recipients to determine a startinglocation for retrieving notifications. In one embodiment, eachnotification retrieval may return an ending location with respect to theblockchain to the recipient, and the recipient may request a newretrieval from a starting location the same as the ending location ofthe previous retrieval. In one embodiment, the recipient may request anew retrieval from a starting location different from the endinglocation of the previous retrieval to remedy situations when thepreviously-retrieved notifications are lost.

These and other features of the systems, methods, and non-transitorycomputer readable media disclosed herein, as well as the methods ofoperation and functions of the related elements of structure and thecombination of parts and economies of manufacture, will become moreapparent upon consideration of the following description and theappended claims with reference to the accompanying drawings, all ofwhich form a part of this specification, wherein like reference numeralsdesignate corresponding parts in the various figures. It is to beexpressly understood, however, that the drawings are for purposes ofillustration and description only and are not intended as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a network environment associated with a blockchain inaccordance with some embodiments.

FIG. 2 illustrates a framework for implementing blockchain transactionsin accordance with some embodiments.

FIG. 3 illustrates a network environment associated with a system forblockchain-based notification in accordance with some embodiments.

FIG. 4 illustrates an architecture associated with a system forblockchain-based notification in accordance with some embodiments.

FIG. 5 illustrates a network environment associated with a system forimplementing various examples of functionalities associated withdecentralized identifiers and verifiable claims in accordance with someembodiments.

FIGS. 6A and 6B illustrate methods for creating a decentralizedidentifier in accordance with some embodiments.

FIG. 7 illustrates a method for authenticating a decentralizedidentifier using DID authentication services in accordance with someembodiments.

FIG. 8 illustrates a method for authenticating a decentralizedidentifier using an identity management application in accordance withsome embodiments.

FIG. 9 illustrates a method for issuing a verifiable claim in accordancewith some embodiments.

FIG. 10 illustrates a method for verifying a verifiable claim inaccordance with some embodiments.

FIG. 11 illustrates a method for creating a decentralized identifierusing an agent service in accordance with some embodiments.

FIG. 12 illustrates a method for authenticating a decentralizedidentifier using an agent service in accordance with some embodiments.

FIG. 13 illustrates a method for authenticating a decentralizedidentifier on behalf of a verifier or an owner in accordance with someembodiments.

FIG. 14 illustrates a method for issuing a verifiable claim using anagent service in accordance with some embodiments.

FIG. 15 illustrates a method for verifying a verifiable claim using anagent service in accordance with some embodiments.

FIG. 16 illustrates a method for blockchain-based notification inaccordance with some embodiments.

FIG. 17 illustrates a flowchart of a method for blockchain-basednotification in accordance with some embodiments.

FIG. 18 illustrates a block diagram of a computer system forblockchain-based notification in accordance with some embodiments.

FIG. 19 illustrates a block diagram of a computer system in which any ofthe embodiments described herein may be implemented.

DETAILED DESCRIPTION

Embodiments described herein provide methods, systems, and apparatusassociated with an ecosystem for decentralized identity management thatmay provide unique and verifiable identities to entities. Adecentralized identifier (DID) for an entity may allow the entity toobtain full control over its identity as well as information associatedwith the identity. For example, the entity may be a business entityhaving many users or be one of the users. Verifiable claims (VCs) mayallow for authorizations, endorsements, and acknowledgements amongdifferent entities. In a business setting, a service or product providermay use its customers' DIDs and VCs to identify and authenticate thecustomers and to provide services or products accordingly.

In some embodiments, a DID may be a unique identifier indicating amapping relationship between a real-world entity and an online identity.The DID may comprise a URL scheme identifier, an identifier for a DIDmethod, and a DID method-specific identifier. Each DID may point to acorresponding DID document. The DID document may comprise descriptivetext in a preset format (e.g., JSON-LD) about the DID and the owner ofthe DID. The DID may serve as a uniform resource identifier (URI) forlocating the DID document. The DID document may comprise variousproperties such as contexts, DID subject, public keys, authentication,authorization and delegation, service endpoints, creation, control,updates, proof, extensibility, other suitable properties, or anycombination thereof. These properties may be manifested as parameters ofthe DID document associated with a DID of an owner. For example, for thecontroller parameter, a DID document of a first DID may log a second DIDfor controlling the first DID (e.g., an owner of the second DID being anentity entrusted to manage the first DID as a controller). For anotherexample, for the creator parameter, a DID document of a first DID maylog a second DID that created the first DID (e.g., an owner of thesecond DID being an entity that created the first DID on behalf of theowner of the first DID). The DID document may define or point toresources defining a plurality of operations that can be performed withrespect to the DID.

In some embodiments, a VC may provide verifiable online informationabout an entity's qualities, characteristics, relationships, and otherrelevant information. A VC may comprise descriptive text in a presetformat (e.g., JSON-LD) that describes one or more declarations regardinga DID (e.g., age of the owner of the DID, educational background of theowner of the DID) and an endorsement of an entity for the declaration. AVC may comprise various properties such as contexts, identifiers, types,credential subject, issuer, issuance date, proofs, expiration, status,presentations, other suitable properties, or any combination thereof.The VC may specify a type of its claim, which may indicate a structureof the claim. This may facilitate automatic processing by the VC issuerand VC verifiers.

Owners of DIDs may participate in the identity management system indifferent roles. For example, an individual may desire to use theservices provided by a business entity, which requires proof that theindividual is over 18 years of age. The individual may be an owner of aDID and may request a VC issued by a government agency that providesverification of citizens' ages. The business entity may verify the VC toascertain that the individual meets the age requirement. In thisscenario, the individual may be a DID owner and a VC holder; thegovernment agency may be a VC issuer, and the business entity may be aVC verifier. As another example, a user may issue a VC to a firstbusiness allowing the first business to use the user's data stored by asecond business. In this case, the user may act as a VC issuer; thefirst business may act as a DID owner and VC holder; the second businessmay act as a VC verifier.

Some embodiments integrate various components, such as blockchainnetworks, cloud applications, agent services, resolver services, userapplications, application programing interface (API) services, keymanagement systems (KMS), identity authentication systems and othersuitable components, to enable functionalities such as creation andauthentication of DIDs and issuance and verification of VCs. In someembodiments, an online platform integrating one or more of thesecomponents may facilitate a business entity in smoothly creating DIDsand issuing VCs for its users. The business entity may interact with theonline platform via one or more API interfaces and trust a plurality ofcryptographic keys to the online platform. The online platform may offeragent services that perform various operations related to DIDs and VCson behalf of the business entity and/or its users. Alternatively, theonline platform may provide software development kits (SDKs) that can beintegrated into applications of the business entity for directlyperforming operations related to DIDs and VCs. The online platform mayalso facilitate the business entity's management of relationshipsbetween DIDs, accounts maintained by the business entity, and identitiesof real-world individuals corresponding to the DIDs and accounts.

FIG. 1 illustrates a network environment associated with a blockchain inaccordance with some embodiments. As shown, in the environment 100, aclient-side computing device 111 may couple to a server end 118, and theserver end 118 and a Node B may couple to a blockchain system 112through various communication networks. Similarly, the server end 118may optionally couple to more blockchain systems similar to theblockchain system 112 such as blockchain system 113, blockchain system114, etc. Each blockchain system may maintain one or more blockchains.

In some embodiments, the client-side computing device 111 may compriseone or more servers (e.g., Node C) and one or more other computingdevices (e.g., Node A1, Node A2, Node A3). Node A1, Node A2, and Node A3may couple to Node C. In some embodiments, Node C may be implemented byan entity (e.g., website, mobile phone Application, organization,company, enterprise), which has various local accounts (e.g., localaccounts assessed from Node A1, Node A2, Node A3). For example, a mobilephone Application may have millions of end-users accessing theApplication's server from respective user accounts. The Application'sserver may correspondingly store millions of user accounts. Thecomponents of the client-side computing device 111 and their arrangementmay have many other configurations.

In some embodiments, the blockchain system 112 may comprise a pluralityof blockchain nodes (e.g., Blockchain Node 1, Blockchain Node 2,Blockchain Node 3, Blockchain Node 4, Blockchain Node i, etc.) thatmaintain one or more blockchains (e.g., public blockchain, privateblockchain, consortium blockchain, etc.). Other blockchain systems(e.g., blockchain system 113, etc.) may comprise a similar arrangementof blockchain nodes maintaining another blockchain. Each blockchain nodemay be found in one or more blockchain systems. The blockchain nodes mayinclude full nodes. Full nodes may download every block and blockchaintransaction and check them against the blockchain's consensus rules. Theblockchain nodes may form a network with one blockchain nodecommunicating with another. The order and the number of the blockchainnodes as shown are merely examples for illustration. The blockchainnodes may be implemented in servers, computers, etc. For example, eachblockchain node may be implemented in a server or a cluster of servers.The cluster of servers may employ load balancing. Each blockchain nodemay correspond to one or more physical hardware devices or virtualdevices coupled together via various types of communication methods suchas TCP/IP. Depending on the classifications, the blockchain nodes mayalso be referred to as full nodes, Geth nodes, consensus nodes, etc.

In some embodiments, Node B may include a lightweight node. Alightweight node may not download the complete blockchain, but mayinstead just download the block headers to validate the authenticity ofthe blockchain transactions. Lightweight nodes may be served by andeffectively dependent on full nodes (e.g., blockchain nodes in theblockchain system 112) to access more functions of the blockchain. Thelightweight nodes may be implemented in electronic devices such aslaptops, mobile phones, and the like by installing an appropriatesoftware. In one embodiment, Node B may send a blockchain transaction tothe blockchain system 112 for adding to the blockchain.

In some embodiments, there may be many more client-side computingdevices coupled to the server end 118 similar to client-side computingdevice 111. The server end 118 may provide Blockchain-as-a-Service(BaaS) and be referred to as a BaaS cloud. In one embodiment, BaaS is acloud service model in which clients or developers outsourcebehind-the-scenes aspects of a web or mobile application. BaaS mayprovide pre-written software for activities that take place onblockchains, such as user authentication, database management, andremote updating. The BaaS cloud may be implemented in a server, servercluster, or other devices. In one embodiment, the BaaS cloud provides anenterprise-level platform service based on blockchain technologies. Thisservice may help clients to build a secure and stable blockchainenvironment as well as manage the deployment, operation, maintenance,and development of blockchain easily. The service features highsecurity, high stability, ease-of-use, and openness and sharing. Basedon the abundant security strategies and multi-tenant isolation of cloud,the BaaS cloud can provide advanced security protection using chipencryption technologies. Based on highly reliable data storage, thisservice provides end-to-end and highly available services that can scaleup quickly without interruption. The BaaS cloud can provide enhancedadministrative functions to help clients to build an enterprise-levelblockchain network environment. The BaaS cloud can provide nativesupport for standard blockchain applications and data, supportmainstream open-source blockchain technologies like Hyperledger Fabricand Enterprise Ethereum—Quorum, to build an open and inclusivetechnology ecosystem.

In the environment 100, each of the systems, nodes, and devices may beinstalled with appropriate software (e.g., application programinterface) and/or hardware (e.g., wires, wireless connections) to accessother devices of the environment 100. In general, the systems, nodes,and devices may be able to communicate with one another through one ormore wired or wireless networks (e.g., the Internet) through which datacan be communicated. Each of the systems, nodes, and devices may includeone or more processors and one or more memories coupled to the one ormore processors. The memories may be non-transitory andcomputer-readable and configured with instructions executable by one ormore processors to cause the one or more processors to performoperations described herein. The instructions may be stored in thememories or downloaded over a communications network without necessarilybeing stored in the memories. Although the systems, nodes, and devicesare shown as separate components in this figure, it will be appreciatedthat these nodes and devices can be implemented as single devices ormultiple devices coupled together. For example, Node B may bealternatively integrated into Blockchain Node 2.

The devices such as Node A1, Node A2, Node A3, Node B, and Node C may beinstalled with an appropriate blockchain software for initiating,forwarding, or accessing blockchain transactions. The term “blockchaintransaction” may refer to a unit of task executed in a blockchain systemand recorded in the blockchain upon verification. In some embodiments,the server end 118 may construct a blockchain contract based oninformation obtained from Node A1, A2, or A3. The server end 118 may addthe blockchain contract in a blockchain transaction. After the serverend 118 submits the blockchain transaction to the blockchain system, theblockchain nodes may verify the blockchain transaction for adding to theblockchain. If the blockchain transaction is added to the blockchain,the blockchain contract is deployed on the blockchain and initiated at acertain state. Through one or more additional blockchain transactions,the deployed blockchain contract may be invoked to update the certainstate.

Blockchain transactions may be verified according to a consensus rule.For example, a POW (proof-of-work) consensus process is provided below.Notwithstanding, other types of consensus processes such as POS(proof-of-stake), DPOS (delegate-proof-of-stake), and PBFT (practicalByzantine Fault Tolerance) may be similarly applied to the disclosedsystems and methods.

In some embodiments with respect to blockchain transaction verification,after receiving a blockchain transaction request of an unconfirmedblockchain transaction, a recipient blockchain node may perform somepreliminary verification of the blockchain transaction. For example,Blockchain Node 1 may perform the preliminary verification afterreceiving a blockchain transaction from Node C. Once verified, theblockchain transaction may be stored in a database of the recipientblockchain node (e.g., Blockchain Node 1), which may also forward theblockchain transaction to one or more other blockchain nodes (e.g.,Blockchain Node 3, Blockchain Node 4). Similarly, the each blockchainnode may comprise or couple to a memory storing a database. The databasemay store a plurality of unconfirmed blockchain transactions. Afterreceiving the blockchain transaction, the one or more other blockchainnodes may repeat the preliminary verification and broadcasting processdone by the recipient blockchain node.

For verification, each blockchain node may select some of the blockchaintransactions from the database according to its preference and form theminto a proposed new block for the blockchain. The blockchain node mayperform “mining” of the proposed new block by devoting computing powerto solve complex mathematical problems. If the blockchain transactioninvolves a blockchain contract, the blockchain nodes may execute theblockchain contract locally in respective virtual machines (VMs). Tohandle the blockchain contracts, each blockchain node of the blockchainnetwork runs a corresponding VM and executes the same instructions inthe blockchain contract. A VM is a software emulation of a computersystem based on computer architectures and provides functionality of aphysical computer. VM in the blockchain context can be understood as asystem designed to operate as a runtime environment for blockchaincontracts.

A certain blockchain node that successfully mines the proposed new blockof blockchain transactions in accordance with consensus rules may packthe new block into its local copy of the blockchain and multicast theresults to other blockchain nodes. The certain blockchain node may be ablockchain node that has first successfully completed the verification,that has obtained a verification privilege, that has been chosen basedon another consensus rule, etc. Then, the other blockchain nodes mayfollow the same order of execution performed by the certain blockchainnode to locally execute the blockchain transactions in the new block,verify the execution results with one another (e.g., by performing hashcalculations), and synchronize their copies of the blockchain with thatof the certain blockchain node. By updating their local copies of theblockchain, the other blockchain nodes may similarly write suchinformation in the blockchain transaction into respective localmemories. As such, the blockchain contract can be deployed on theblockchain. If the verification fails at some point, the blockchaintransaction is rejected.

The deployed blockchain contract may have an address, according to whichthe deployed contract can be accessed. A blockchain node may invoke thedeployed blockchain contract by inputting certain parameters to theblockchain contract. In one embodiment, a deployed blockchain contractmay be invoked to add or update certain information in the blockchaincontract, thereby updating one or more states in the blockchaincontract. In one embodiment, the one or more states of the blockchaincontract may be retrieved from the blockchain by inquiring acorresponding blockchain transaction added to the blockchain. The mostupdated state may be reflected in the most recent relevant blockchaintransaction. Notwithstanding the above, other types of blockchainsystems and associated consensus rules may be applied to the discloseddevices and methods.

FIG. 2 illustrates a framework for implementing blockchain transactionsin accordance with some embodiments. In some embodiments, theclient-side computing device 111 may transmit information to the serverend 118. The information may be for creating a blockchain account,performing an action based on blockchain contract, etc. The blockchainmay be maintained by the blockchain system 112. The server end 118 mayconstruct a blockchain contract based on the information obtained fromthe client-side computing device 111. The server end 118 may add theblockchain contract in a blockchain transaction A. The server end 118may sign the blockchain transaction on behalf of a user associated withthe client-side computing device 111. For example, the blockchaintransaction A may comprise information such as nonce (e.g., transactionserial number), from (e.g., a blockchain address of the user), to (e.g.,empty if deploying a blockchain contract), transaction fee, signature(e.g., signature of the server end 118, signature of the user managed bythe server end 118), value (e.g., transaction amount), data (e.g., theblockchain contract), etc. Then, the server end 118 may submit theblockchain transaction A to one or more blockchain nodes of theblockchain system 112 for adding to the blockchain.

After the blockchain transaction is added to the blockchain, theblockchain contract is deployed on the blockchain and initiated at acertain state. Through one or more additional blockchain transactions,the deployed blockchain contract may be invoked to update the certainstate. In some embodiments, Node B may construct a signed blockchaintransaction B and transmit it to the blockchain system 112 forexecution. In one embodiment, the blockchain transaction B may beexecuted to invoke the deployed blockchain contract to update a state.In some embodiments, the blockchain transaction B may be programmed insource code at a user-end application 221. For example, a user ormachine may program the blockchain transaction B. Node B may compile thesource code using a corresponding compiler, which converts the sourcecode into bytecode. The blockchain transaction B may compriseinformation such as nonce, from, to, transaction fee, value, signature,data, etc. Node B may send the blockchain transaction B to one or moreblockchain nodes of the blockchain system 112 through a remote procedurecall (RPC) interface 223 for execution. RPC is a protocol that a firstprogram (e.g., user-end application) can use to request a service from asecond program located in another computer on a network (e.g.,blockchain node) without having to understand the network's details.When the first program causes a procedure to execute in a differentaddress space, it is as if a normal (local) procedure call, without theprogrammer explicitly coding the details for the remote interaction.

In some embodiments, on receiving the blockchain transaction (e.g.,blockchain transaction A or B), the recipient blockchain node may verifyif the blockchain transaction is valid. For example, the signature andother formats may be verified. If the verification succeeds, therecipient blockchain node may broadcast the received blockchaintransaction to the blockchain network including various other blockchainnodes. Some blockchain nodes may participate in the mining process ofthe blockchain transaction. The blockchain transaction may be chosen bya certain node for consensus verification to pack into a new block. Ifthe blockchain transaction involves deploying a blockchain contract, thecertain node may create a contract account for the blockchain contractin association with a contract account address. If the blockchaintransaction involves invoking a deployed blockchain contract, thecertain node may trigger its local VM to execute the received blockchaintransaction, thereby invoking the deployed blockchain contract from itslocal copy of the blockchain and updating the states in the deployedblockchain contract. If the certain node succeeds in mining a new block,the certain node may broadcast the new block to other blockchain nodes.

Upon receiving the new block, the other blockchain nodes may performverifications. If a consensus is reached that the new block is valid,the new block is respectively packed to the local copies of theblockchain maintained by the blockchain nodes. The blockchain nodes maysimilarly trigger their local VMs (e.g., local VM 1, local VM i, localVM 2) to execute the blockchain transactions in the new block, thusinvoking local copies of the blockchain (e.g., local blockchain copy 1,local blockchain copy i, local blockchain copy 2) and makingcorresponding updates. The hardware machine of each blockchain node mayhave access to one or more virtual machines, which may be a part of orcouple to the corresponding blockchain node. Each time, a correspondinglocal VM may be triggered to execute the blockchain transaction.Likewise, all other blockchain transactions in the new block will beexecuted. Lightweight nodes may also synchronize to the updatedblockchain.

FIG. 3 illustrates a network environment associated with a system forblockchain-based notification in accordance with some embodiments. Insome embodiments, a user-side system 310 may correspond to an entity.The entity may be a business entity that provides one or more productsor services to a plurality of users. The entity may also be anindividual user, a group of users, an organization, other suitableentities, or any combination thereof. The use-side system 310 maycomprise a plurality of computer systems, data stores, cloud services,mobile applications, other suitable components, or any combinationthereof. The user-side system 310 may comprise a server 311 and adatabase 313. The database 313 may store data associated with aplurality of user accounts of the users of the entity. The entitycorresponding to the user-side system 310 may desire to create andmanage DIDs and VCs for itself as well as its users. It may comprise oneor more software development kits (SDKs) 312 for managing creation andauthentication of DIDs or issuance and verification of VCs.

In some embodiments, to implement functionalities associated with DIDsand VCs, the user-side system 310 may interface with a service-sidesystem 320. In some embodiments, the service-side system 320 asillustrated in FIG. 3 may be equivalent to, be part of, or comprise oneor more components of the server end 118 as illustrated in FIGS. 1 and2. The service-side system 320 may comprise one or more messengers 325,one or more agents 321, one or more resolvers 322, one or more keymanagement systems 323, one or more clouds 324, other suitablecomponents or any combination thereof. The agent 321 may provide variousservices or applications related to DIDs or VCs and maintain databasesmapping account information or other business data from the user-sidesystem 310 to DIDs, VCs, or other information or data stored on one ormore blockchains. The agent 321 may provide one or more applicationprogramming interfaces (APIs), which may be used by the user-side system310 to directly submit requests related to DIDs or VCs. The agent 321may manage communications between the user-side system 310 and theresolver 322 and the cloud 324. The messenger 325 may providenotifications related to DIDs, VCs, or other information or data storedon one or more blockchains for the user-side system 310.

In some embodiments, the agent 321 may be coupled to a key managementsystem (KMS) 323. The KMS 323 may generate, distribute, and managecryptographic keys for devices and applications. It may cover securityaspects from secure generation of keys over the secure exchange of keysto secure key handling and storage. The functionalities of the KMS 323may include key generation, distribution, and replacement as well as keyinjection, storing, and management. The KMS 323 may comprise or becoupled to a trusted execution environment (TEE). The TEE may be anisolated area on the main processor of a device that is separate fromthe main operating system. The TEE may provide an isolated executionenvironment offering security features such as isolated execution,integrity of applications executing with the TEE, along withconfidentiality of their assets. It may guarantee code and data loadedinside to be protected with respect to confidentiality and integrity. Insome embodiments, the KMS 323 may generate one or more cryptographic keypairs in the TEE. Before outputting the cryptographic key pair, the TEEmay encrypt the private key. The encryption of the private key can bebased on various methods or standards, such as Data Encryption Standard(DES), TripleDES, RSA, Advanced Encryption Standard (AES), Twofish, etc.The KMS 323 may store the encrypted private key in association with thepublic key. To use the private key, the KMS 323 may feed the encryptedprivate key to the TEE for decryption and processing.

In some embodiments, the agent 321 may be coupled to a resolver 322,which may comprise software applications for managing interactionsbetween the agent and a blockchain 330 in transactions related to DIDsor VCs (e.g., correspondence between a DID and a DID document). Herein,depending on the context, the blockchain 330 may refer to a blockchainsystem that comprises a decentralized network of nodes that store aledger of records and participate in a consensus process for adding datato the ledger of records or the ledger of records stored, maintained, orupdated by the decentralized network of nodes. When referring to ablockchain system, the blockchain 330 may comprise, be part of, or beembodied in one or more of the blockchain systems 112, 113, and 114illustrated in FIGS. 1 and 2. The resolver 322 may be part of or coupledto the one or more cloud-based services. The one or more cloud-basedservices may be associated with a blockchain-as-a-service (BaaS) cloud324 or other suitable cloud services. The BaaS cloud 324 may constitutea platform that offers various interfaces to one or more blockchains330. It may receive inputs from an external application and facilitatethe creation and execution of operations such as blockchain transactiondeployment, blockchain contract creation and execution, blockchainaccount creation based on the inputs. The BaaS cloud 324 may also obtaininformation and data from one or more blockchains 330 and feed theinformation and data to one or more other systems using the BaaS cloud324. In some embodiments, the agent 321 may be directly coupled to thecloud 324 to use its services. In some embodiments, one or more of theagent 321, the resolver 322, and the KMS 323 may be integrated as partof the BaaS cloud 324 or another suitable online platform.

In some embodiments, the resolver 322 and cloud 324 may be coupled to ablockchain 330. The blockchain 330 may comprise one or more blockchaincontracts 331. One or more of the blockchain contracts 331 may beconfigured to be executed by a virtual machine associated with theblockchain 300 to perform one or more operations associated with DIDsand VCs. The operations may comprise creating a new DID, storing a DIDdocument, updating a DID document, identifying a DID document based on aDID, storing information associated with a VC, retrieving informationassociated with a VC, other suitable operations, or any combinationthereof. The resolver 322 and cloud 324 may be configured to deploy oneor more transactions on the blockchain 330 that invoke one or more ofthe blockchain contracts 331. The transactions may trigger one or moreoperations related to DIDs and VCs.

In some embodiments, the messenger 325 may be coupled to the agent 321,the resolver 322, and the user-side system 310. The messenger 325 mayobtain notifications from the resolver 322, and provide thenotifications to the user-side system 310.

In some embodiments, the network environment may comprise an identityauthentication system 340. The identity authentication system 340 may beused to establish mapping relationships between DIDs and real-worldidentities. The identity authentication system 340 may be associatedwith an entity performing identity authentication for individuals orentities. The identity authentication may be performed based ondocuments, photos, or other suitable materials provided by an individualor entity. The identity authentication may also be performed based ondata that is collected directly, such as photos, fingerprints, passwordinputs, other suitable data, or any combination thereof The identityauthentication system 340 may be coupled to the user-side system 310and/or the service-side system 320. The identity authentication system340 may receive one or more requests from the user-side system 310 orthe service-side system 320 for proofs of identity authentication. Inresponse, the identity authentication system 340 may perform anynecessary identity authentication and send the proofs of identityauthentication back to the requester. The proofs of identityauthentication may comprise, for example, a confirmation message, asecurity key, a unique identification code, other suitable proofs, orany combination thereof. In some embodiments, the identityauthentication system 340 may be coupled to a blockchain system. Theblockchain system connected to by the identity authentication system 340may be the blockchain system 330 that is coupled to the service-sidesystem 320. Alternatively, although FIG. 3 illustrates the identityauthentication system 340 to be coupled to the blockchain system 330,this disclosure contemplates the scenario in which the identityauthentication system 340 is coupled to a different blockchain system.The identity authentication system 340 may have access to the blockchain330 or another suitable blockchain directly or via an intermediatesystem (e.g., the BaaS cloud 324).

The identity authentication system 340 may comprise an identity service341, which may be implemented on one or more servers or cloud platforms.In some embodiments, the identity service 341 may be implemented as partof the service-side system 320 (e.g., the cloud 324). In otherembodiments, the identity service 341 may be implemented on a systemseparate from the service-side system 320. The identity service 341 maybe configured to process requests for identity authentication, tocontrol a client-side application 342 to collect identity data, togenerate proofs of identity authentication, to store or access identityinformation in a database 343, to perform one or more operations on theblockchain 330 (e.g., obtain identity information, store proof ofidentity authentication). In some embodiments, the identityauthentication system 340 may comprise a client-side application 342that is connected to the identity service 341 via a network. Theclient-side application 342 may be dedicated to identity authenticationor may incorporate identity authentication as one of its functions alongwith one or more other functions. The client-side application 342 may beconfigured to collect data associated with a user. The client-sideapplication 342 may further be configured to compare collected data withpre-stored data corresponding to a purported identity of a user toauthenticate the identity of the user. In some embodiments, the identityauthentication system 340 may comprise a database 343 connected to theidentity service 341. The database 343 may store identity informationassociated with a plurality of individuals or entities. The identityinformation may comprise, for example, a proof of identityauthentication, visual features of a person, voice features of a person,a fingerprint of a person, a signature of a person, a passwordassociated with an identity, other suitable identity information, or anycombination thereof

FIG. 4 illustrates an architecture associated with a system forblockchain-based notification in accordance with some embodiments. Insome embodiments, the system may comprise three main components, one ormore agent services 321, one or more resolver services 322, one or moremessenger services 325, and one or more blockchain contracts 331. Theone or more agent services 321 may be configured to process requestsrelated to DIDs and VCs that are received from users. The one or moreagent services 321 may manage mapping relationships between accountinformation on user-side systems 310 and DIDs of the owners of theaccounts. The agent services 321 may comprise a DID agent service API410 for receiving DID-related requests from user-side systems 310.Depending on the nature of a request, it may be fed to a user agent 411for performing operations such as creation and authentication of DIDs oran issue agent 412 for performing operations such as issuance of VCs.The requests from a party desiring to verify a VC may be fed to theverifier agent 413. The one or more agent services 321 may also providea verifiable claim repository 414 for storing one or more VCs. The agentservices 321 may also use one or more memories 415 and one or moredatabases 416. The agent services 321 may be coupled to a KMS 323 and aBaaS Cloud 324. The agent services 321 may be coupled to the resolverservices 322.

In some embodiments, one or more agents of the agent services 321 maysend one or more requests to a DID resolver API 420 associated with theresolver services 322. The resolver services 322 may be configured toprocess interactions between the agent services 321 and the blockchain330. The resolver services 322 may perform operations such as obtainingdata from the blockchain 300, adding data to the blockchain 330,creating blockchain contracts 331, deploying transaction to theblockchain 330 to invoke blockchain contracts 331, other suitableoperations, or any combination thereof The resolver services 322 maycomprise a DID resolver 421 configured to manage DIDs and DID documentsstored on the blockchain 330 and a VC resolver 422 configured to manageVCs for DIDs created based on the blockchain 330. The resolver services322 may also comprise a listener 424 for obtaining data from theblockchain 331. The listener 424 may store obtained data to a database423. The data may be used by the DID resolver 421 and the VC resolver422. The DID resolver 421, VC resolver 422, and listener 424 may becoupled to a BaaS cloud 324 for interactions with the blockchain 330.

In some embodiments, the messenger services 325 may comprise a messengerservice API 430 for receiving queries from the user-side system 310 andfor providing notifications to the user-side system 310. The messengerservice API 430 may obtain notifications placed in a message queue bythe DID resolver API 420. The message queue may be stored in a database452. The messenger service API 430 may filter and categorize theobtained notifications and store in a memory 451.

In some embodiments, the blockchain 330 may comprise one or moreblockchain contracts (331 a, 331 b, 331 c) for managing DIDs and DIDdocuments and comprise one or more contracts (331 d, 331 e, 331 f) formanaging VCs. The contracts may be executed by one or more virtualmachines associated with the blockchain 330 to perform operations suchas creating DIDs, storing DID documents, updating DID documents, storinginformation associated with VCs, other suitable operations, or anycombination thereof

FIG. 5 illustrates a network environment associated with a system forimplementing various examples of functionalities associated withdecentralized identifiers and verifiable claims in accordance with someembodiments. Components of the network environment may be categorizedinto three layers 510, 520, and 530. In some embodiments, the bottom orcore layer 510 may comprise one or more blockchains 330, which maycomprise one or more blockchain contracts (331 g, 331 h, 331 i) that canbe executed to perform operations related to DIDs and VCs. Theblockchain 330 may store a plurality of DIDs and a plurality of DIDdocuments corresponding to the DIDs. The blockchain contracts (331 g,331 h, 331 i) may be configured to manage mapping relationships betweenDIDs and DID documents, as well as creation and changes to DIDdocuments. The blockchains 330 may be accessible to one or moreresolvers (322 a, 322 b) for operations related to DIDs and VCs. Theresolvers (322 a, 322 b) may be configured to provide to an externalsystem services such as searching for DID documents or data contained inDID documents based on inputted DIDs. One or more method libraries 511may also be available for external systems to adopt to interact with theblockchain 330.

In some embodiments, the middle or enhancement layer 520 may compriseone or more user agents 411, one or more issuer agents 412, or one ormore verifier agents 413. The middle or enhancement layer 520 mayfurther comprise a messenger 325 coupled to a memory 451 and a database452. In some embodiments, the blockchain 330 may comprise a consortiumblockchain, which may or may not be directly accessible to users thatare not consensus nodes of the consortium blockchain. A user agent 411may provide an interface for an ordinary user to interact with theblockchain. In some embodiments, the user agent 411 may be configured tocreate one or more DIDs, authenticate one or more DIDs, interact withone or more verifiable data registry 521 or one or more DID hubs 522,send notifications to an owner of a DID, perform other suitablefunctionalities, or any combination thereof. Here, a DID hub 522 maycomprise a system in which an owner of a DID stores its sensitive data.The owner may grant certain other entities (e.g., institutions issuingverifiable claims) access to data stored in the DID hub 522. Averifiable data registry 521 may comprise a VC repository for storingand managing the VCs issued to an owner of a DID. An issuer agent 412may comprise one or more APIs (e.g., REST API) or SDKs. The issuer agent412 may be configured to issue one or more verifiable claims, withdrawone or more verifiable claims, check and inspect an existing verifiableclaim, publish a template for verifiable claims, maintain a template forverifiable claims, perform other suitable operations, or any combinationthereof. A verifier agent 413 may comprise one or more APIs (e.g., RESTAPI) or SDKs and be configured to verify a verifiable claim or performone or more other suitable operations. In some embodiments, the layer520 may also comprise one or more code libraries (e.g., DID resolvelibrary 523, DID authentication library 524) that can be adopted andused to interact with the DID resolvers 322 or directly with theblockchain 330. The code libraries may be packaged into one or more SDKsand be used to perform functionalities such as DID authentication,interactions with the blockchain 300, or interfacing with blockchaincontracts 331. The issuer agent 412 and verifier agent 413 may be usedby key participants in the network environment associated with DIDs andVCs such as entities able to perform know-your-customer (KYC)authentication or endorsement for users or to issue or verify verifiableclaims (e.g., government institutions, banks, financial serviceproviders). The key participants may provide third-party services thatcan be integrated via connections with the issuer agent 412, theverifiable agent 413, or other suitable components of the networkenvironment.

In some embodiments, the upper or extension layer 530 may comprise oneor more external services or applications related to DIDs and VCs. Theservices or applications may comprise one or more issuer applications531, one or more verifier applications 532, an identity managementapplication 533, a service application 534, one or more other suitableservices or applications, or any combination thereof An issuerapplication 531 may correspond to an entity (e.g., governmentinstitution, banks, credit agency) issuing verifiable claims signed orendorsed by the entity for users. The issuer application 531 may operateon a user-side system 310. The issuer application 531 may comprise anissuer verifiable claim manager service which may allow an issuer tomanage issued VCs, maintain their status (e.g., validity), or performother suitable operations. The issuer application 531 may interact withthe layers 510 and 520 via a connection or interface with the issueragent 412 or one or more code libraries 523 and 524. A verifierapplication 532 may correspond to an entity (e.g., service provider,credit issuer) needing to verify verifiable claims to ascertain a user'sinformation (e.g., identity, age, credit score). The verifierapplication 532 may operate on a user-side system 310. The verifierapplication 532 may interact with layers 510 and 520 via a connection orinterface with the verifier agent 413 or one or more code libraries 523and 524. The identity management application 533 may be installed on aclient device or terminal associated with a user. The user may be a DIDowner, which may be an individual, a business, an organization, anapplication, or any other suitable entity. The identity managementapplication 533 may allow a user to manage cryptographic key pairsassociated with DIDs, original data, or VCs, to receive notificationsfrom a user agent 411, to authenticate a DID, to grant access to data,to use a VC, to perform other suitable operations, or any combinationthereof The identity management application 533 may interact with thelayers 510 and 520 via a connection or interface with the user agent411. The service application 534 may also be coupled to the user agent411 and be configured to manage functions related to DIDs or VCs for oneor more users or accounts. The service application 534 may also becoupled to the messenger 325 and be configured to send queries for oneor more DIDs and to obtain corresponding notifications.

FIGS. 6-10 illustrate example operations associated with DIDs or VCsperformed by one or more user-side systems 310, one or more service-sidesystems 320, one or more resolvers 322, one or more clouds 324, one ormore messengers 325, or one or more blockchain systems 330. In someembodiments, a user-side system 310 may manage one or more DIDs or oneor more VCs by interfacing with a service-side system 320 (e.g.,comprising, e.g., a DID resolver 322) and a blockchain 330 storing DIDsand DID documents. The user-side system 310 may use one or more SDKs 312for managing DIDs that are compatible with methods associated with theDIDs. The SDKs 312 may be integrated with one or more applications usedby the user-side system 310. The user-side system 310 may also interfacewith one or more service endpoints for storing verifiable claims, one ormore service endpoints for storing status information for verifiableclaims, one or more service endpoints for authentication of DIDs, othersuitable systems, or any combination thereof

FIGS. 6A and 6B illustrate methods for creating a decentralizedidentifier in accordance with some embodiments. The operations of themethods presented below are intended to be illustrative. Depending onthe implementation, the methods may include additional, fewer, oralternative steps performed in various orders or in parallel.Furthermore, one or more steps performed in either of methods 6A and 6Bmay be replaced with one or more suitable steps performed in the othermethod. The devices or systems performing certain steps as illustratedin FIGS. 6A and 6B may also be substituted by other suitable devices orsystems to perform the same steps. The suitable devices or systems maycomprise sub-systems, parent systems, or counterpart systems withsimilar functionalities. As an example, one or more steps performed bythe user-side system 310 in FIG. 6A may be performed by the identitymanagement application 533 in FIG. 6B and vice versa. As anotherexample, one or more steps performed by the service-side system 320 maybe performed by the resolver 322, which may be a sub-system of theservice-side system 320. Although this specification describesparticular devices or systems performing particular steps, thisspecification contemplates any suitable devices or systems performingany suitable steps for creating a decentralized identifier.

In some embodiments, as illustrated in FIG. 6A, the user-side system 310may create a DID for each of one or more of its users. The user-sidesystem 310 may control the cryptographic key pair associated with theDID and use the cryptographic key pair to perform various operationsrelated to the DID including, for example, signing blockchaintransactions, signing verifiable claims, or authentication of the DID.The user-side system 310 may comprise an SDK 312 for performing thevarious operations. The SDK 312 may also manage various interactionsbetween the user-side system 310 and various interfaces provided by theservice-side system 320. The interfaces may comprise an interface forassignment of DIDs, an interface for creation of DID documents, aninterface for adding DID documents to the blockchain 330, an interfacefor searching DID documents, other suitable interfaces, or anycombination thereof The interfaces may be provided by way of, forexample, software programs and network ports. In response to requestsreceived at the interfaces, the service-side system 320 may performcorresponding operations and return results via the interfaces toappropriate external systems. The method illustrated in FIG. 6A maystart at step 602, in which a server 311 of a user-side system 310 mayobtain identity authentication of a user for whom it is going to obtaina DID. The identity authentication may have been performed by theidentity authentication system 340 or another suitable system. In otherembodiments, the user-side system 310 may have obtained a proof ofidentity authentication for the user from an identity authenticationsystem 340. The proof of identity authentication for the user maycomprise a proof of real-name authentication (e.g., based ongovernment-issued identity documents), a proof of real-personauthentication (e.g., based on a photo of the user taken based oninstructions of the identity authentication system 340), a proof ofother identity authentication, or any combination thereof. The user-sidesystem 310 may also generate or retrieve a cryptographic key pairincluding a public key and a private key for use to create the DID.

At step 604, the server 311 may invoke a functionality of an SDK 312 forcreating a new DID. The server 311 may provide various information tothe SDK 312 for invoking the functionality. The information may comprisean account identifier for the user corresponding to the to-be-createdDID, a public key or private key of the cryptographic key pair generatedfor the DID, specification of one or more services associated with theto-be-created DID, a callback network address associated with the server311 for return of confirmations or other communications, other suitableinformation, or any combination thereof The account identifier maycorrespond to a business or service account of the user with an entityassociated with the user-side system 310. At step 606, the user-sidesystem 310 may send a request for creating a new DID to the service-sidesystem 320 using the SDK 312. The service-side system 320 may therebyobtain the request for creating a DID. The request may comprise a publickey of a cryptographic key pair, which may have been generated by theuser-side system 310. FIG. 6A illustrates a scenario where the requestfor creating the DID is received from a computing device associated witha first entity (e.g., user-side system 310) for creating the DID onbehalf of a second entity (e.g., user). The request may furthercomprise, in addition to the public key, an account identifierassociated with the second entity (e.g., user), profile informationassociated with the second entity (e.g., user), information about one ormore services associated with the DID, a callback address associatedwith the first entity (e.g., user-side system 310) or the second entity(e.g., user), other suitable information, or any combination thereof. Analternative scenario is illustrated in FIG. 6B where the request forcreating the DID is received directly from a computing device associatedwith an entity to own the DID. In some embodiments, the request may bein the form of an application programming interface (API) message to oneor more of the interfaces provided by the service-side system.

In response to the request obtained from the user-side system 310, theservice-side system 320 may create, based on the public key in therequest, a blockchain account associated with a blockchain 330. At step608, the service-side system 320 may send a request to the blockchainsystem 330 for creating a new blockchain account. Here, the request maybe directly sent to one or more blockchain nodes of the blockchain 330in the form of one or more blockchain transactions or be sent via a BaaSCloud 324 or other suitable interface systems associated with theblockchain 330. After sending the request, at step 610, the service-sidesystem 320 may obtain an indication from blockchain 330 that a newblockchain account has been created. The blockchain account may beassociated with an address on the blockchain 330. The service-sidesystem 320 may obtain information associated with the newly-createdblockchain address.

Then, the service-side system 320 may create a DID based on informationassociated with the blockchain account. At step 612, the service-sidesystem 320 may assign a DID to the user based on the blockchain account.The service-side system 320 may assure that the assigned DID is uniqueby determining that the DID is not duplicative of any existing DIDassociated with the blockchain 330. According to this embodiment, theDID may be assigned and determined to be unique prior to theconstruction or upload of a DID document corresponding to the DID. Thismay effectively prevent potential failed attempts to upload the DIDdocument due to duplication of the DID, and thus save processing andcomputation efforts in creating and uploading the DID document. Theservice-side system 320 may associate the DID with the user's accountwith the user-side system 310 by storing a mapping relationship betweenthe account identifier and the created DID. The service-side system 320may further store a status of the DID. As an example and not by way oflimitation, the status of the DID may indicate whether the DID has beenregistered to the blockchain 330 or whether a corresponding DID documenthas been stored in the blockchain 330. At step 614, the service-sidesystem 320 may send a message back to the SDK 312 associated with theuser-side system 310. The message may comprise information associatedwith the newly created DID.

At step 616, the user-side system 310 may use the SDK 312 to create aDID document associated with the DID. The DID document may compriseinformation associated with the DID such as the public key associatedwith the DID, authentication information associated with the DID (e.g.,one or more authentication methods), authorization informationassociated with the DID (e.g., a DID associated with a controller),delegation information associated with the DID (e.g., one or moredelegation methods), one or more services associated with the DID (e.g.,one or more types of services such as credential repository service andagent service), one or more service endpoints associated with the DID(e.g., URI for each of one or more service endpoints), other suitableinformation, or any combination thereof The SDK 312 may create the DIDdocument based on information received from the server 311 when theserver 311 invokes the SDK 312 at step 604. The user-side system 310 mayfurther use the SDK 312 to create a blockchain transaction for addingthe DID document to the blockchain 330. The blockchain transactioncreated at this stage may or may not be complete and valid. In someembodiments, the blockchain transaction created by the user-side system310 may lack information associated with the blockchain 330, one or moreblockchain contracts associated with the blockchain 330, a digitalsignature, other suitable information, or any combination thereof

At step 618, the SDK 312 may send the DID document to service-sidesystem 320. If the SDK 312 has created a blockchain transaction, it maysend the blockchain transaction to the service-side system 320, whichmay comprise the DID document. At this step, the SDK 312 may request theservice-side system 320 to provide a hash value associated with acompleted but unsigned blockchain transaction for adding the DIDdocument to the blockchain 330. After obtaining the DID documentcorresponding to the DID from the user-side system 310, the service-sidesystem 320 may generate or complete a blockchain transaction for addingthe DID document to the blockchain 330. The blockchain transaction mayinvoke a blockchain contract 331 previously deployed on the blockchain330 for managing relationships between DIDs and corresponding DIDdocuments. The blockchain contract 331 invoked may comprise one or moreinterfaces, such as an interface for adding one or more DID documents tothe blockchain 330. The one or more interfaces of the blockchaincontract 331 may comprise executable code corresponding to one or moreexecutable functions of the blockchain contract 331. To generate theblockchain transaction, the service-side system 320 may include one ormore information items in the blockchain transaction. The one or moreinformation items may comprise an address associated with the blockchain330, an identifier of a blockchain contract 331 associated with theblockchain transaction, version information of the blockchain contract331 associated with the blockchain transaction, information of one ormore interfaces of the blockchain contract 331 associated with theblockchain transaction, other suitable information, or any combinationthereof The information added by the service-side system 320 to theblockchain transaction may comprise public or other suitable informationassociated with the blockchain system 330, blockchain contracts on theblockchain 330, or other information necessary for creating a validblockchain transaction. The service-side system 320 may automaticallypopulate such information and relieve the user-side system 310 of theburden of keeping track of such information. This may reduce thetechnical capabilities required for the user-side system 310 to add aDID document to the blockchain 330.

The blockchain transaction generated by the service-side system 320based on the DID document received from the user-side system 310 may beunsigned at this stage. The service-side system 320 may determine a hashvalue of the unsigned blockchain transaction according to a hashfunction acceptable to the blockchain system 330. At step 620, theservice-side system 320 may send the hash value of the unsignedblockchain transaction to the user-side system 310. Then, at step 622,the SDK 312 associated with the user-side system 310 may create adigital signature on the hash value. As an example, the digitalsignature may be created by encrypting the hash value using the privatekey of the cryptographic key pair associated with the owner of the DIDthat is received from the server 311. At step 624, the SDK 312 mayreturn the digital signature to the service-side system 320, therebyauthorizing the blockchain transaction. After receiving the digitalsignature from the user-side system 310 at step 624, the service-sidesystem 320 may add the digital signature to the unsigned blockchaintransaction to generate or complete the blockchain transaction foradding the DID document to the blockchain. Then, at step 626, theservice-side system 320 may send the blockchain transaction to one ormore blockchain nodes associated with the blockchain 330 for adding tothe blockchain. At step 628, the service-side system 320 may obtaininformation from the blockchain 330 confirming successful storage of theDID document in the blockchain 330. At step 630, the service-side system320 may return a confirmation message to the SDK 312. The confirmationmessage may comprise the DID and DID document that have been created.Then, at step 632, the SDK 312 may provide the DID and DID document tothe server 311. Here, the SDK 312 may send information associated withthe DID and the DID document based on information associated with thecallback address received from the server 311. At step 634, the server311 may send the user a notification confirming successful creation ofthe DID and the corresponding DID document.

In some embodiments, as illustrated in FIG. 6B, a user may create a DIDfor itself using one or more interfaces provided by the service-sidesystem 320 and without using a service provided by a user-side system310. The user may comprise an individual, a business, an organization,another suitable entity, or any combination thereof. As an example, theuser may use an identity management application 533 or another suitablesoftware or hardware system to interact with the service-side system320. The identity management application 533 may be developed by anentity associated with the service-side system 320 and provided forinstallation on a client device associated with the user. The identitymanagement application 533 may be configured to manage interactions withvarious interfaces provided by the service-side system 320. The methodillustrated in FIG. 6B may start at step 642, the user may provide oneor more inputs to the identity management application 533 in order torequest creation of a DID for the user. The identity managementapplication 533 may request inputs from the user verifying thereal-world identity of the user. Alternatively, the identity managementapplication 533 may have obtained identity authentication informationassociated with the user previously and may be configured to retrievesuch information, for example, when the user logs in the identitymanagement application 533.

At step 644, the identity management application 533 may generate acryptographic key pair for the user. The cryptographic key pair maycomprise a public key and a private key to be used to create the DIDassociated with the user. At step 646, the identity managementapplication 533 may send a request for creating a new DID to theservice-side system 320. At step 648, the service-side system 320 maysend a request to a blockchain system 330 for creating a new blockchainaccount. Here, the request may be directly sent to one or moreblockchain nodes of the blockchain 330 in the form of one or moreblockchain transactions or be sent via a BaaS Cloud 324 or othersuitable interface systems associated with the blockchain 330. Then, atstep 650, the service-side system 320 may obtain from the blockchain 330information indicating that a new blockchain account has been created.The blockchain account may be associated with an address on theblockchain 330. The information obtained by the service-side system 330may comprise information associated with the newly-created blockchainaddress. It may comprise information sufficient to create the DID. Atstep 652, the service-side system 320 may assign a unique DID to theuser according to information associated with the blockchain account. Atstep 654, the service-side system 320 may send a message back to theidentity management application 533. The message may compriseinformation associated with the newly created DID.

In some embodiments, a DID document may be created and stored on theblockchain 330. At step 656, the identity management application 533 maygenerate a DID document and add the public key associated with thenewly-created DID and other suitable information (e.g., authenticationinformation) to the DID document. The identity management application533 may add information associated with one or more service endpoints(e.g., information associated with an authentication service endpoint,information associated with a verifiable claim repository) to the DIDdocument. The authentication service endpoint and the verifiable claimrepository may be provided as part of the service-side system 320 or beprovided by third-party systems. Then, at step 658, the identitymanagement application 533 may generate one or more blockchaintransactions for adding the DID document to the blockchain 330. Theidentity management application 533 may generate a hash value of theblockchain transaction and generate a digital signature for thetransaction using the private key associated with the DID at step 660.Alternatively, the identity management application 533 may interact withthe service-side system 320 in a manner similar to the interactionsbetween the user-side system 310 and the service-side system 320 asillustrated by steps 618, 620, and 622 of FIG. 6A in order to generateand sign the blockchain transaction. At step 662, the identitymanagement application 533 may send the DID document as well as theblockchain transaction to the service-side system 320 for sending to theblockchain system 330. At step 664, the service-side system 320 may sendthe one or more transactions to the blockchain system 330. The one ormore transactions may invoke a blockchain contract 331 for managing DIDsand DID documents on the blockchain 330. At step 666, the service-sidesystem 320 may obtain information from the blockchain 330 indicatingthat the DID document has been successfully stored. At step 668, theservice-side system 320 may forward a confirmation to the identitymanagement application 533. At step 670, the identity managementapplication 533 may provide a notification comprising informationassociated with the created DID and DID document for display to theuser.

FIG. 7 illustrates a method for authenticating a decentralizedidentifier using DID authentication services in accordance with someembodiments. The operations of the method presented below are intendedto be illustrative. Depending on the implementation, the method mayinclude additional, fewer, or alternative steps performed in variousorders or in parallel. In some embodiments, a user owning a DID may useDID authentication services provided by a business entity to achieveauthentication of its ownership of the DID. The owner may trust apublic-private key pair corresponding to the DID to the business entityfor storage. The owner may provide a network location (e.g., identifiedby a URL) of the DID authentication services as a service endpoint forauthentication of the DID. The location identifier of the DIDauthentication services may be included in a “service” field of the DIDdocument associated with the DID.

In some embodiments, a verifier 532 (e.g., a service provider needing toverify information of a customer) may initiate a DID authenticationprocess using an SDK 312. At step 702, the verifier 532 may obtain theDID provided by a purported owner. At step 704, the verifier 532 maycall the SDK 312 to create a DID authentication challenge. The verifier532 may input to the SDK 312 the DID to be authenticated and a networkaddress (e.g., a URL) to which a response to the challenge is to besent. At step 706, the SDK 312 may send a query to a resolver 322 forthe DID document associated with the DID to be authenticated. At step708, the resolver 322 may formulate a blockchain transaction invoking ablockchain contract 331 for managing DIDs and send the blockchaintransaction to one or more blockchain nodes associated with theblockchain 330 for execution. As a result, the resolver 322 may obtainthe DID document corresponding to the DID at step 710 and forward it tothe SDK 312 at step 712. At step 714, the verifier 532 may use the SDK312 to create a DID authentication challenge based on the obtained DIDdocument. In some embodiments, the DID authentication challenge maycomprise a ciphertext created by encrypting original text using a publickey associated with the DID that is recorded in the DID document. Thechallenge may also comprise a network address to which a response is tobe sent. At step 716, the verifier 532 may obtain information associatedwith the authentication service endpoint for the DID from the DIDdocument. At step 718, the verifier 532 may use the SDK 312 to send thechallenge to the DID authentication services associated with the DID.

In some embodiments, after obtaining the DID authentication challengefrom the verifier 532, the DID authentication services may obtainconsent from the owner for such authentication request at step 720. Ifthe owner provides consent or permission for the identityauthentication, the DID authentication services may call its version ofthe SDK 312 to create a response to the DID authentication challenge atstep 722. In some embodiments, the response to the DID authenticationchallenge may comprise plaintext that is the result of decrypting theciphertext in the challenge using the private key associated with theDID. The SDK 312 may return the response to the DID authenticationservices at step 724, which may then send the response to the networkaddress provided by the verifier 432 at step 726. Upon receiving theresponse to the DID authentication challenge, the verifier 532 may callits SDK 312 at step 728 to check the response. At step 730, the SDK 312may determine whether the response proves that the user providing theDID is the owner of the DID. In some embodiments, the SDK 312 may checkthe response by comparing decrypted text in the response with theoriginal text that was used to create the DID authentication challenge.If the response is determined to be correct, the SDK 312 may return amessage to the verifier 532 indicating the DID is a valid proof ofidentity of the user at step 732. At step 734, the verifier 532 maynotify the user as to the validity of the DID.

FIG. 8 illustrates a method for authenticating a decentralizedidentifier using an identity management application in accordance withsome embodiments. The operations of the method presented below areintended to be illustrative. Depending on the implementation, the methodmay include additional, fewer, or alternative steps performed in variousorders or in parallel. In some embodiments, a user may use a terminalfor managing DIDs, which may comprise an identity management applicationor another suitable application. The application may comprise a versionof the SDK 312. In this example, the user may need services from aservice provider (i.e., verifier), which requires verification that theuser owns a particular DID in order to provide its services. The usermay send a service request to the verifier. The service request may bein the form of an HTTP request.

At step 802, the user may call the identity management application 533to provide authentication information for the service request. The usermay provide the original service request as an input to the SDK 312included in the identity management application 533. At step 804, theSDK 312 may sign the content of the original service request using aprivate key of a cryptographic key pair associated with the DID. The SDK312 may be used to add the DID and a digital signature for the originalservice request to the original service request to create a signedservice request. In case the original service request is a HTTP request,the SDK 312 may add the DID and the digital signature to a header of theHTTP request. At step 806, the SDK 312 may send the signed servicerequest to the verifier 532.

In some embodiments, the verifier 532 may call its version of an SDK 312to authenticate the DID included in the signed service request at step808. At step 810, the SDK 312 may obtain the DID and the digitalsignature included in the signed service request. In case the signedservice request is an HTTP request, the DID and the digital signaturemay be obtained from the header of the HTTP request. At step 812, theSDK 312 may send a query to a resolver 322 for the DID documentassociated with the DID to be authenticated. At step 814, the resolver322 may formulate a transaction invoking a blockchain contract 331 formanaging DIDs and send the transaction to one or more blockchain nodesassociated with the blockchain 330 for execution. As a result, theresolver 322 may obtain the DID document corresponding to the DID atstep 816 and forward it to the SDK 312 at step 818. At step 820, the SDK312 associated with the verifier 532 may check the signed servicerequest to determine whether it is from the owner of the DID based onthe obtained DID document. In some embodiments, the SDK 312 may decryptthe digital signature using a public key obtained from DID document, andcheck the decryption result against a hash value of the original servicerequest to determine if the public key is associated with the key usedto create the digital signature in the signed service request. If so,the SDK 312 may determine that the service request from the user isvalid. It may then send it to the verifier 532 for processing at step822. The verifier 532 may process the service request and provideappropriate services to the user at step 824. Then, the verifier 532 maysend a response to the user at step 826 to confirm completion of therequested services.

FIG. 9 illustrates a method for issuing a verifiable claim in accordancewith some embodiments. The operations of the method presented below areintended to be illustrative. Depending on the implementation, the methodmay include additional, fewer, or alternative steps performed in variousorders or in parallel. In some embodiments, an issuer 531 may issue a VCto a user. The VC may be used as a proof of certain facts orcharacteristics of the user as endorsed by the issuer 531.

At step 902, the issuer 531 may obtain a DID associated with the userand a proof of the fact to be included in the VC. Here, the proof of thefact to be included in the VC may be based on materials submitted by theuser to the issuer 531, information or data obtained by the issuer 531from third-party systems, in-person verification of the facts, othersuitable sources of proof, or any combination thereof. After obtainingthe DID and the proof, the issuer 531 may call an SDK 312 associatedwith creation of VCs to initiate a process for creating the VC at step904. The message from the issuer 531 may comprise a statement of theproven fact or a claim about the user. The SDK 312 may create a VCdocument including the statement using a cryptographic key pairassociated with the issuer 531. In some embodiments, the VC may includea digital signature created based on a private key associated with theissuer 531. At step 908, the SDK 312 may update a locally-stored statusof the VC.

At step 910, the SDK 312 may send a query to a resolver 322 for the DIDdocument associated with the DID for which the VC is issued. At step912, the resolver 322 may formulate a transaction invoking a blockchaincontract 331 for managing DIDs and send the transaction to one or moreblockchain nodes associated with the blockchain 330 for execution. As aresult, the resolver 322 may obtain the DID document corresponding tothe DID at step 914 and forward it to the SDK 312 at step 916. At step918, the SDK 312 may identify a VC service endpoint associated with theDID of the user for storing VCs. The VC service endpoint may correspondto a VC repository 414 used by the user or the owner of the DID. Then atstep 920, the issuer may use the SDK 312 to send the VC to the VCrepository 414 for storage. The VC may also include informationassociated with a VC status service endpoint, which may store andprovide status information for the VC. In some embodiments, theinformation may comprise a network address (e.g., URL) for an issueagent service used by the issuer 531 to keep status of VCs. The VCstatus service endpoint may or may not be associated with the VCrepository 414. The SDK 312 may provide the current status of the newlygenerated VC to the VC status service endpoint for storing. The statusof the VC may be stored on a blockchain.

FIG. 10 illustrates a method for verifying a verifiable claim inaccordance with some embodiments. The operations of the method presentedbelow are intended to be illustrative. Depending on the implementation,the method may include additional, fewer, or alternative steps performedin various orders or in parallel. In some embodiments, a user mayprovide a VC to another party (e.g., a verifier 532) to prove a factstated in the VC. The VC may be provided after the verifier 532 hasverified that the user is the owner of a DID associated with the VC.

At step 1002, the verifier 532 may call an SDK 312 comprising codelibraries associated with VC verification to verify the VC. The SDK 312may identify from the VC (e.g., in a “credential status” field)information associated with a VC status service endpoint for the VC. TheVC status service endpoint may be associated with an issuer 531. At step1004, the SDK 312 may send a query to the issuer 531 for the status ofthe VC. In response, at step 1006, the issuer 531 may call an SDK 312 toobtain the status of the VC. The SDK 531 may obtain the status of theVC. As an example, the SDK 312 may determine that the VC has a validstatus and may return the information to the issuer 531 at step 1008.Then, at step 1010, the issuer may return the valid status informationto the SDK 312 associated with the verifier 532.

The verifier 532 may obtain an identifier associated with the issuer 531of the VC. For example, the identifier may be a DID of the issuer 531.At step 1012, the SDK 312 may send a query to a resolver 322 for apublic key associated with the DID of the issuer 531 of the VC. At step1014, the resolver 322 may formulate a transaction invoking a blockchaincontract 331 for managing DIDs and send the transaction to one or moreblockchain nodes associated with the blockchain 330 for execution. As aresult, the resolver 322 may obtain the public key corresponding to theDID at step 1016 and forward it to the SDK 312 associated with theverifier 532 at step 1018. At step 1020, the SDK 312 associated with theverifier 532 may verify the VC based on a digital signature includedtherein and the public key associated with the issuer 531 of the VC. Ifthe VC is verified, the SDK 312 may send a confirmation to the verifier532 at step 1022.

FIGS. 11-15 illustrate example operations associated with DIDs or VCsperformed by one or more user-side systems 310, one or more service-sidesystems 320, one or more agents 321, one or more resolvers 322, one ormore clouds 324, one or more blockchain systems 330, one or more KMSs,or other suitable systems, applications, services. In some embodiments,a user-side system 310 may manage one or more DIDs or VCs by interactingwith an online platform integrating one or more of the aforementionedcomponents via one or more API interfaces (e.g., REST API). Theuser-side system 310 may trust confidential information such ascryptographic key pairs to the online platform for secure keeping.

FIG. 11 illustrates a method for creating a decentralized identifierusing an agent service in accordance with some embodiments. Theoperations of the method presented below are intended to beillustrative. Depending on the implementation, the method may includeadditional, fewer, or alternative steps performed in various orders orin parallel. In some embodiments, a user-side system 310 associated withan entity may use one or more agent services 321 to create one or moreDIDs for one or more users of the entity and correlate the DIDs withinternal accounts or identifications (e.g., service IDs) maintained bythe entity. In order to create DIDs for its users, the entity may havebeen authenticated by the online platform as a trusted entity and mayhave made a commitment to provide truthful information. In someembodiments, the entity may have been issued a VC by a bootstrap issuerDID to certify that it is authenticated by an authoritative entity. Theentity may be required to authenticate the identities of its users. Theuser-side system 310 may use one or more KMSs 323 and the secureenvironment (e.g., TEE) that they provide to manage cryptographic keysassociated with the created DIDs and to map the cryptographic keys tothe internal accounts or identifications maintained by the entity. Withthe help of the agent services 321, the user-side system 310 may useservices associated with DIDs without keeping a record of the DIDs.Instead, it may simply provide its internal account information oridentification information for identification of the DIDs via one ormore interfaces associated with the agent services 321.

In some embodiments, an online platform for managing DIDs may receive arequest for creating a DID. The request may be from a first entity onbehalf of a second entity for creating the DID for the second entity. Inthe example illustrated by FIG. 11, an entity (e.g., first entity) maycreate a DID for a user (e.g., second entity), who may have an accountwith the business entity. In some embodiments, the entity mayauthenticate the identity of a user before creating a DID for the user.For example, at step 1102 of FIG. 11, a server 311 of a user-side system310 associated with the entity may perform identity authentication orotherwise obtain identity authentication information for the user. Theentity may have authenticated the identity of the user earlier and maymaintain such information in a database. At step 1104, the server 311may retrieve such information. Then, the server 311 may send the requestfor creating the DID to an agent service API 410 associated with a useragent 411 associated with the online platform. The request may comprisean account identifier corresponding to the user. The request may takethe form of an API message. At step 1006, the agent service API 410 maysend a request to a user agent 411 for creating the DID.

At step 1108, the user agent 411 may check the request for requiredinformation. In some embodiments, to create a DID for a user, the entitymay be required to have an existing DID for itself. The user agent 411may check the request to determine that the sender of the request has anexisting DID and to determine the DID associated with the sender. Insome embodiments, the entity may be required to provide a proof ofidentity authentication for the user. The proof of identityauthentication may comprise a proof of real-person authentication, aproof of real-name authentication, another suitable proof ofauthentication, or any combination thereof. For example, a proof ofreal-name authentication may be based on a user's office identification(e.g., government-issued ID). An example proof may, for example, be anumber created by applying a hash function (e.g., SHA-256) to acombination of an ID type, ID number, and a number of the user. Such aproof may ensure unique correspondence with a particular user whilemaintaining sensitive information of the user confidential.

In some embodiments, the user agent 411 may determine whether therequest for creating a DID comprises a proof of identity authentication.The proof of identity authentication may comprise a proof of real-nameauthentication, a proof of real-person authentication, proofs of othersuitable methods of identity authentication, or any combination thereof.If the user agent 411 determines that the request does comprise theproof of identity authentication, the user agent 411 may accept therequest based on the determination. If the user agent 411 determinesthat the request for creating a DID does not comprise a proof ofidentity authentication, the user agent 411 may reject the request.Alternatively, the user agent 411 may send to the server 311 a requestfor the proof of identity authentication. The user agent 411 may thenreceive the required proof of identity authentication from the server311. The user agent 411 may also use other methods to obtain identityauthentication of the user.

At step 1109, the user agent 411 may obtain the proof of identityauthentication for the user corresponding to the DID to be created. Insome embodiments, the user agent 411 may directly obtain the proof ofidentity authentication based on the received request or otherinformation received from the server 311. The user-side system 310 mayhave obtained the proof by performing identity authentication or byusing an identity service 341. The user-side system 310 may include aproof of identity authentication in the request for creating the DID orinclude means to obtain the proof (e.g., a link). In some embodiments,the user-side system 310 may delegate the function of sending requestsfor creating DIDs to an identity service 341. The server 311 may sendinformation associated with one or more users, for whom it intends tocreate DIDs, to the identity service 341. The identity service 341 mayperform identity authentication on the users or confirm that identityauthentication on the users has been successfully completed. Theidentity service 341 may create one or more requests for creating DIDsbased on the information received from the server 311, the requestsincluding proofs of identity authentication for the users. In someembodiments, DID documents created in response to requests from theidentity service 341 may comprise a field (e.g., a “creator” field)indicating that the DID is created based on identity authentication bythe identity service 341. In some embodiments, after the DID is createdbased on identity authentication by identity service 341, the identityservice 341 may issue a VC to the DID certifying the real-world identityof the owner of the DID. In some embodiments, before another issuerissues a VC to the owner of the DID, this other issuer may require theVC issued by the identity service 341 as a proof of identityauthentication of the DID owner.

In some embodiments, the user agent 411 may obtain the proof of identityauthentication independently by using an identity service 341. In someembodiments, the identity service 341 may correspond to an entitytrusted by the service-side system 320. The entity may perform identityauthentication on users (e.g., real-name authentication, real-personauthentication). The identity authentication may comprise collectingvarious identity information (e.g., name, date of birth, address,appearance features, fingerprint) associated with an individual thatcorresponds to an identity and compare the collected information withinformation maintained by authoritative sources (e.g., governmentagencies). After successful authentication of an individual's identity,the identity service 341 may store a record of the successfulauthentication (e.g., a proof of identity authentication) and identityinformation associated with the individual in association withidentifiers of the individual, such as an account or a service ID. Theidentity service 341 may store identity information and proofs ofidentity authentication in a database 343. Alternatively, the identityservice 341 may store identity information and proofs of identityauthentication in a blockchain 330. In some embodiments, the identityservice 341 may create one or more blockchain transactions for savingthe identity information in the blockchain 330 and send the one or moreblockchain transactions to one or more blockchain nodes associated withthe blockchain 330. Alternatively, the identity service 341 may interactwith the blockchain 330 via, for example, the BaaS cloud 324. Theidentity service 341 may send the BaaS cloud 324 a request to store theidentity information and proof of identity authentication on theblockchain 330. The user agent 411 may send a request to the identityservice 341 for a proof of identity authentication of a user. The usermay correspond to a request for creating a DID. The identity service 341may send back the requested proof of identity authentication.

In some embodiments, the user agent 411 may obtain a DID in response toa request without obtaining the proof of identity verification. The DIDcreated in this manner may be assigned a status of “authenticationpending.” It may be mapped to a dummy account identifier. The status maybe represented in the DID document corresponding to the DID, saved in asystem storing status information for DIDs, or be saved by the useragent 411. The operations that can be performed in relation to a DIDwith such a status may be limited. For example, the owner of the DID maybe prohibited from issuing VCs or being issued VCs. The status of“authentication pending” may be removed after a proof of identityauthentication is provided to the user agent 411. The identity service341 may send the user agent 411 the proof of identity authenticationproactively, or upon request by the user-side system 310 or the useragent 411. After receiving the proof, the user agent 411 may updatestatus information stored in association with the DID. Furthermore, theuser agent 411 may store a mapping relationship between the DID and anaccount identifier associated with the user whose identity has beenauthenticated. Further details about identity authentication aredescribed in relation to FIGS. 15-18.

After obtaining the proof of identity authentication, the user agent 411may create a key alias corresponding to the proof of identityauthentication for the user at step 1110. In some embodiments, the useragent 411 may obtain, in response to receiving the request, a public keyof a cryptographic key pair. The public key may later be used as a basisfor creating the DID. In some embodiments, the user agent 411 may obtainthe public key from the KMS 323. At step 1112, the user agent 411 maysend a request to the KMS 323 for generating and storing a cryptographickey pair. The KMS 323 may generate a cryptographic key pair. In someembodiments, the KMS 323 may cause the cryptographic key pair to begenerated in a TEE associated with the KMS 323. After the key pair isgenerated, the KMS 323 may obtain a public key and an encrypted privatekey from the TEE. At step 1114, the KMS 323 may send the public key tothe user agent 411.

In some embodiments, the online platform may obtain the DID based on thepublic key. At step 1116, the user agent 411 may send a request forcreating a new DID to the resolver 322 The request may comprise thepublic key. In response, the resolver 322 may generate, based on thepublic key, one or more blockchain transactions for creating the DID andadding a DID document associated with the DID to a blockchain.Alternatively, the DID resolver may send a request to the BaaS cloud 324for generation of such transactions. For example, at step 1118, theresolver 322 may send a request to a blockchain system 330 for creatinga new blockchain account. Here, the request may be directly sent to oneor more blockchain nodes of the blockchain 330 in the form of one ormore blockchain transactions or be sent to a BaaS Cloud 324 or othersuitable interface systems associated with a blockchain 330. Theblockchain transactions may invoke one or more blockchain contractsconfigured for managing DIDs. In response to the request from theresolver 322, at step 1120, the DID resolver may obtain an indicationfrom the blockchain 330 or the cloud 324 that a new blockchain accountis successfully created. The blockchain account may be associated withan address on the blockchain 330. Information obtained by the resolver322 may comprise information associated with the newly-createdblockchain address. It may directly comprise a newly-created DID or atleast information sufficient to construct the DID. At step 1122, theresolver 322 may send a message back to the user agent 411. The messagemay comprise information associated with the newly created DID.

In some embodiments, a DID document may be created and stored in theblockchain 330. At step 1124, the user agent 411 may generate a DIDdocument and add the public key associated with the newly-created DIDand authentication information to the DID document. At step 1126, theuser agent 411 may add information associated with one or more serviceendpoints (e.g., information associated with an authentication serviceendpoint, information associated with a verifiable claim repository) tothe DID document. The authentication service endpoint and the verifiableclaim repository 414 may be provided as part of the online platform. TheDID document may comprise one or more public keys associated with theobtained DID, authentication information associated with the obtainedDID, authorization information associated with the obtained DID,delegation information associated with the obtained DID, one or moreservices associated with the obtained DID, one or more service endpointsassociated with the obtained DID, a DID of a creator of the obtainedDID, other suitable information, or any combination thereof. In someembodiments, the DID document may comprise a “creator” field containingidentification information (e.g., DID) of the entity that sent therequest for creating the DID on behalf of the user. The “creator” fieldmay serve as a record of the entity that authenticated of the identityof or endorsed the owner of the DID. Then, at step 1128, the user agent411 may generate one or more blockchain transactions for storing the DIDdocument to the blockchain 330. The user agent 411 may also generate oneor more hash values of the blockchain transactions.

In some embodiments, for the one or more blockchain transactions to beexecuted by one or more nodes of the blockchain 330, they are requiredto be signed using the private key associated with the DID. The useragent 411 may obtain such a digital signature from the KMS 323. At step1130, the user agent 411 may send a request to the KMS 323 for signing ablockchain transaction using the private key of the cryptographic keypair associated with the DID. The request may comprise the hash value ofthe transaction and a public key associated with the DID. The KMS 323may create a digital signature for the transaction. In some embodiments,the digital signature may be generated in a TEE associated with the KMS323. The KMS 323 may identify an encrypted private key associated withthe public key and feed the encrypted private key to the TEE. Theencrypted private key may be decrypted within the TEE and used togenerate the digital signature for the transaction. The digitalsignature may then be fed back to the KMS 323. At step 1132, the useragent 411 may receive from the KMS a signed version of the blockchaintransaction.

At step 1134, the user agent 411 may send the DID document as well asthe signed blockchain transaction to the resolver 322 for sending to theblockchain system. At step 1136, the resolver 322 may send one or moretransactions to the blockchain system (e.g., one or more blockchainnodes, a BaaS Cloud 324). The transactions may invoke a blockchaincontract 331 for managing DIDs and DID documents on the blockchain 330.At step 1138, the resolver 322 may obtain information from theblockchain 330 indicating that the DID document has been successfullystored. At step 1140, the resolver 322 may forward a confirmation touser agent 411.

At step 1142, after a DID and its corresponding DID document have beencreated, the user agent 411 may update the database 416 to store amapping relationship among the DID, an account identifier of the user, aproof of identity authentication of the user, a service ID of the user,a public key associated with the DID, a key alias associated with theuser or the proof of identity authentication, other suitableinformation, or any combination thereof. In some embodiments, themapping relationship may be stored in an encrypted form. To store themapping relationship, the user agent 411 may calculate a hash value fora combination the DID and one or more items of the other identificationinformation. In some embodiments, such a hash value may be stored aspart of the DID document. The stored mapping relationship may allow theuser agent 441 to identify the DID based on information received fromthe user-side system 310. In some embodiments, the user agent 411 mayreceive a request associated with the obtained DID, wherein the requestcomprises the account identifier and then identify the obtained DIDbased on the mapping relationship between the account identifier and theobtained DID. In other embodiments, the user agent 441 may receive arequest for a proof of identity authentication, wherein the requestcomprises a DID and then locate the proof of identity authenticationbased on the mapping relationship between the proof of identityauthentication and the DID. In some embodiments, the user agent 411 maystore a recovery key for recovering the private key corresponding to theDID in association with identification information of the user. In thismanner, the user agent 411 may allow the user to take control over theDID using the recovery key. Then, at step 1144, the user agent 411 maysend information associated with the DID to the server 311, which maysend a notification to the user at step 1146 to inform the user of thesuccessful creation of the DID.

FIG. 12 illustrates a method for authenticating a decentralizedidentifier using an agent service in accordance with some embodiments.The operations of the method presented below are intended to beillustrative. Depending on the implementation, the method may includeadditional, fewer, or alternative steps performed in various orders orin parallel. In some embodiments, a party (e.g., verifier) may desire toauthenticate that another party (e.g., purported owner of DID) is thetrue owner of a DID. The authentication process may be facilitated byagent services 321 available to both parties.

In some embodiments, at step 1202, the verifier 532 may obtain a DIDprovided by a purported owner. At step 1204, the verifier 532 may send arequest to an agent service API 410 for creating a DID authenticationchallenge. The request may comprise the DID to be authenticated and anetwork address (e.g., a URL) to which a response to the challenge is tobe sent. The network address may be accessible to the verifier 532. Atstep 1206, the request may be forwarded from the agent service API 410to a verifier agent 413 configured to perform operations related toauthentication of DIDs. At step 1208, the verifier agent 413 may send aquery to a resolver 322 for the DID document associated with the DID tobe authenticated. At step 1210, the resolver 322 may formulate atransaction invoking a blockchain contract 331 for managing DIDs andsend the transaction to one or more blockchain nodes associated with theblockchain 330 for execution. As a result, the resolver 322 may obtainthe DID document corresponding to the DID at step 1212 and forward it tothe verifier agent 413 at step 1214. At step 1216, the verifier agent413 may create a DID authentication challenge based on the obtained DIDdocument. In some embodiments, the DID authentication challenge maycomprise a ciphertext created by encrypting original text using a publickey associated with the DID that is recorded in the DID document. Thechallenge may also comprise the network address associated with theverifier, to which a response is to be sent. At step 1218, the verifieragent 413 may obtain information associated with the authenticationservice endpoint for the DID from the DID document. At step 1220, theverifier agent 413 may store an identifier of the challenge in relationto information associated with the challenge in a memory using akey-value structure. For example, the verifier agent 413 may store achallenge ID associated with the challenge in association with the DIDto be authenticated, a plaintext used to create the cyphertext, and thenetwork address for sending the response to the challenge. At step 1222,the verifier agent 413 may send the challenge to the DID authenticationservices associated with the DID based on information from the DIDdocument.

In some embodiments, after obtaining the DID authentication challengefrom the verifier agent 413, the DID authentication services may obtainconsent from the owner of the DID for responding to such a challenge atstep 1224. If the owner provides consent or permission for the identityauthentication, the DID authentication services may send a request to anagent service API 410 associated with a user agent 411 for a response tothe DID authentication challenge at step 1226. At step 1228, the agentservice API 410 may call a corresponding functionality of the user agent411 for creation of a response to the challenge. The response to thechallenge may require restoration of the plaintext used to create theciphertext included in the challenge using a private key associated withthe DID to be authenticated. At step 1230, the user agent 411 may sendthe cyphertext from the challenge to the KMS 323 for decryption alongwith identification information associated with the DID that isrecognized by the KMS 323. The KMS 323 may store a plurality ofpublic-private key pairs in association with identification informationfor accounts or DIDs corresponding to the key pairs. Based on theidentification information received from the user agent 411, the KMS 323may identify the public-private key pair associated with the DID. Insome embodiments, the KMS 323 may store the public key and an encryptedversion of the private key. It may send the encrypted private key to aTEE associated with the KMS 323 for decryption. The private key may thenbe used to decrypt the ciphertext within the TEE. At step 1232, the useragent 411 may obtain the decrypted plaintext from the KMS 323.

At step 1234, the user agent 411 may generate a response to thechallenge using the plaintext and send the response back to the DIDauthentication services. The response may comprise a challengeidentifier that was contained in the original challenge. At step 1236,the DID authentication services may send the response to the networkaddress provided by the verifier 532. Then, at step 1238, the verifier532 may forward the response to the verifier agent 413 for checking. Theverifier agent 413 may first compare the challenge identifier in theresponse with one or more challenge identifiers stored in the memory 415to identify information associated with the challenge corresponding tothe response at step 1240. Then at step 1242, the verifier agent 413 maydetermine if the purported owner of the DID is the actual owner. In someembodiments, the verifier agent may determine if the plaintext containedin the response is identical to the plaintext used to create theciphertext in the challenge. If so, the verifier agent 413 may determinethat authentication is success. The verifier agent 413 may send aconfirmation message to the verifier at step 1244, which may forward theconfirmation message to the owner of the DID at step 1246.

FIG. 13 illustrates a method for authenticating a decentralizedidentifier on behalf of a verifier or an owner in accordance with someembodiments. The operations of the methods presented below are intendedto be illustrative. Depending on the implementation, the methods mayinclude additional, fewer, or alternative steps performed in variousorders or in parallel. Furthermore, one or more steps performed in anyof the methods illustrated in FIG. 13 may be replaced with one or moresuitable steps performed in another one of the methods. The devices orsystems performing certain steps as illustrated in FIG. 13 may also besubstituted by other suitable devices or systems to perform the samesteps. The suitable devices or systems may comprise sub-systems, parentsystems, or counterpart systems with similar functionalities. As anexample, one or more steps performed by the user-side system 310 may beperformed by the identity management application 533 and vice versa. Asanother example, one or more steps performed by the service-side system320 may be performed by the resolver 322 or agent 321, which may be asub-system of the service-side system 320. Although this specificationdescribes particular devices or systems performing particular steps,this specification contemplates any suitable devices or systemsperforming any suitable steps for authenticating decentralizedidentifiers.

In some embodiments, one party (e.g., verifier 532) may desire toauthenticate that another party (e.g., purported owner of DID) is thetrue owner of a DID. The service-side system 320 may provide one or moreservices and interfaces to either or both of the parties to facilitatethe parties in completing one or more steps of an authenticationprocess. The methods illustrated by FIG. 13 may comprise one or moresteps that are replaceable with or can be used to replace one or moresteps of the method illustrated in FIG. 12.

In some embodiments, as illustrated in FIG. 13, a purported DID ownermay interact with the service-side system 320 through a user-side system310 a associated with a first entity. A verifier 532 of the DID mayinteract with the service-side system 320 through a user-side system 310b associated with a second entity. The first entity and the secondentity may or may not be the same entity. As an example and not by wayof limitation, the purported DID owner may correspond to an individualuser, and the verifier 532 may correspond to a service provider needingto authenticate an identity of the user before providing a service tothe user. It may be the case that neither the purported DID owner northe verifier 532 has the technical capabilities or needs to directlymanage DID-related operations. They may rely on the user-side systems310 a and 310 b to interface with the service-side system 320 in orderto perform DID-related operations. For example, the user-side system 310a may be authorized to control one or more operations associated withthe DID on behalf of the owner of the DID.

The method illustrated in FIG. 13 may start at step 1311, where thepurported DID owner may provide a DID to the verifier 532. In responseto obtaining the DID, the verifier 532 may begin the authenticationprocess for the DID. At step 1312, the verifier 532 may provide to thepurported DID owner a DID authentication challenge. In some embodiments,the DID authentication challenge may comprise a plaintext (e.g., a pieceof text selected by the DID verifier). In order to prove its ownershipof the DID, the purported DID owner may need to provide a digitalsignature on the plaintext using a private key of a cryptographic keypair associated with the DID. At step 1313, the purported DID owner mayforward the DID authentication challenge to the user-side system 310 a.In this scenario, the purported DID owner and the user-side system 310 amay have entrusted the management of the cryptographic key pairassociated with the DID to the service-side system 320. At step 1314,the user-side system 310 a may send a request to the service-side system320 (e.g., to the user agent 411 in the service-side system 320) for adigital signature on the plaintext included in the DID authenticationchallenge. The request may comprise the DID to be authenticated and theplaintext.

The service-side system 320 may obtain the request for creating thedigital signature from the user-side system 310 a. From the request, theservice-side system 320 may obtain the plaintext and informationassociated with the DID. At step 1315, the service-side system 320 mayobtain one or more permissions associated with a sender of the requestfor creating the digital signature, and may determine, based on theobtained one or more permissions and the information associated with theDID, whether the sender of the request for creating the digitalsignature is authorized to control one or more operations associatedwith the DID. The service-side system 320 may ascertain the identity ofthe sender of the request based on encrypted or other securecommunication with the sender. For example, the service-side system 320may check and determine whether the sender of the request is the ownerof the DID, a controller or creator of the DID, or a user-side system310 that is authorized to manage one or more operations associated withthe DID. If it is determined that the sender of the request for creatingthe digital signature is authorized to control the one or moreoperations associated with the DID, the service-side system 320 maycreate the digital signature per the request. Otherwise the service-sidesystem 320 may reject the request. In some embodiments, the service-sidesystem 320 may additionally check a status of the DID. For example, theservice-side system 320 may determine whether the DID has beenregistered on the blockchain 330 or whether a DID document associatedwith the DID has been stored on the blockchain 330. In some embodiments,the service-side system 320 may only proceed with providing the digitalsignature if the DID has been registered on the blockchain 330 and is ina fully functional status.

If the service-side system 320 accepts the request for creating thedigital signature, it may proceed to step 1316. At step 1316, theservice-side system 320 may identify a blockchain account associatedwith the DID. The service-side system 320 may query the blockchain 330for such blockchain account information and obtain such information atstep 1317. The service-side system 320 may use an identifier of theblockchain account corresponding to the DID to identify a cryptographickey pair associated with the DID. For example, the service-side system320 may obtain a key identifier based on the identifier of theblockchain account and access the cryptographic key pair based on thekey identifier. Then, at step 1318, the service-side system 320 maycreate the digital signature on the plaintext based on the request forcreating the digital signature. The digital signature may be created byencrypting a hash value of the plaintext using a private key associatedwith the DID. In some embodiments, the service-side system 320 may usethe KMS 323 to generate the digital signature. The service-side system320 may send instructions to the KMS 323 for signing the plaintext usingthe private key associated with the DID. Then, the service-side system320 may obtain the digital signature from the KMS 323. For example, theservice-side system 320 may identify a blockchain account associatedwith the DID, determine an identifier for the private key associatedwith the DID based on the identified blockchain account associated withthe DID, and include the identifier for the private key associated withthe DID in the instructions. In some embodiments, the digital signatureobtained from the KMS 323 may have been generated in a TEE.

At step 1319, the service-side system 320 may return the digitalsignature on the plaintext to the user-side system 310 a. The user-sidesystem 310 a may generate a response to the DID authentication challengebased on the digital signature and send the response to the purportedDID owner at step 1320. The response may comprise information associatedwith the DID (e.g., the DID), information associated with the DIDauthentication challenge (e.g., an identifier of the DID authenticationchallenge), the plaintext included in the DID authentication challenge,the digital signature, other suitable information, or any combinationthereof. Then, at step 1321, the purported DID owner may provide theresponse to the verifier 532.

After receiving the response to the DID authentication challenge fromthe purported DID owner, the verifier 532 may initiate a process forauthenticating the ownership of the DID based on the response. At step1322, the verifier 532 may provide the response to the user-side system310 b. At step 1323, the user-side system 310 b may forward the responseto the service-side system 320 (e.g., to the verifier agent 413 in theservice-side system 320) as part of a request for authenticating theDID. The request may comprise the DID, the plaintext associated with theDID authentication challenge, the digital signature on the plaintext,other suitable information, or any combination thereof. In someembodiments, the request may comprise the response to the DIDauthentication challenge, which may comprise part or the entirety of theinformation included in the request. The service-side system 320 mayinitiate a process for authenticating the DID in response to obtainingthe request for authenticating the DID. In some embodiments, theservice-side system 320 may check for satisfaction of one or morecriteria before initiating the process. For example, the service-sidesystem 320 may check whether a creator of the DID authenticationchallenge (e.g., the verifier 532) owns a DID managed by theservice-side system 320, whether the DID to be authenticated has a validstatus (e.g., whether the DID has been registered on the blockchain330), whether another suitable criterion is satisfied, or anycombination thereof. If all the required criteria, if any, aresatisfied, the service-side system 320 may initiate the process forauthenticating the DID.

In some embodiments, the service-side system 320 may obtain a public keyassociated with the DID. In some embodiments, the service-side system320 may identify a blockchain 330 associated with the DID and obtain thepublic key from the identified blockchain. At step 1324, theservice-side system 320 may query the blockchain 330 for the public keyassociated with the DID. Then, at step 1325, the service-side system 320may obtain the public key from the blockchain 330. For example, theservice-side system 320 may send a blockchain transaction to one or moreblockchain nodes of the blockchain 330 to retrieve a DID documentcorresponding to the DID. The blockchain transaction may compriseinformation associated with the DID and may invoke a blockchain contractfor managing relationships between DIDs and corresponding DID documents.For example, the blockchain transaction may call an interface of theblockchain contract that is executable to retrieve informationassociated with one or more DID documents corresponding to one or moreDIDs. The service-side system 320 may obtain the DID document from theblockchain 330 and retrieve the public key from the DID document.

At step 1326, the service-side system 320 may verify the digitalsignature based on the plaintext and the public key. In one embodiment,the service-side system 320 may determine, based on the obtained publickey and the plaintext, whether the digital signature on the plaintext iscreated based on a private key corresponding to the DID. For example,the service-side system 320 may calculate a hash value of the plaintextand decrypt the digital signature using the public key to obtain adecrypted value. The service-side system 320 may compare the calculatedhash value and the decrypted value to determine whether they are thesame. If so, the service-side system 320 may determine that the digitalsignature is created based on the private key corresponding to thepublic key. At step 1327, the service-side system 320 may return aresult of authentication to the user-side system 310 b (the sender ofthe request for authenticating the DID). If the service-side system 320determines that the digital signature on the plaintext is created basedon the private key corresponding to the DID, the service-side system 320may generate and send a message confirming authentication of the DID.This confirms that the purported DID owner is the actual owner of theDID. Otherwise, the service-side system 320 may generate and send amessage indicating that the authentication of the DID has failed. Atstep 1328, the user-side system 310 b may forward the result to theverifier 532, the creator of the DID authentication challenge.Alternatively, the service-side system 320 may directly return theresult to the verifier 532, the creator of the DID authenticationchallenge.

FIG. 14 illustrates a method for issuing a verifiable claim using anagent service in accordance with some embodiments. The operations of themethod presented below are intended to be illustrative. Depending on theimplementation, the method may include additional, fewer, or alternativesteps performed in various orders or in parallel. In some embodiments, afirst entity (e.g., an issuer) may desire to issue a VC for a secondentity (e.g., a user) to testify as to a fact related to the secondentity. The first entity may be referred to as an issuer of theverifiable claim, and the second entity may be referred to as a subjectof the verifiable claim. The process of issuing the VC may befacilitated by agent services 321 available to the entities.

In some embodiments, an agent service API 410 may receive, from theissuer 531, a request for creating an unsigned VC for a DID associatedwith the user at step 1402. At step 1404, the agent service API 410 maycall the issuer agent 412 to execute operations to generate a new VC. Atstep 1406, the issuer agent 412 may create a VC based on the requestreceived from the issuer 531. The VC may comprise a message that isincluded in the request. In some embodiments, the VC may comprise anencrypted version of the message for confidentiality reasons. Themessage may comprise a claim or statement regarding the user or othersuitable information or data that may be conveyed to a party with accessto the VC. In some embodiments, the VC may comprise a claimcorresponding to identity authentication of the user (e.g., real-nameauthentication, real-person authentication). The request may comprise aDID of the user. The issuer agent 412 may directly create the VC basedon the DID. Alternatively, the request may comprise an accountidentifier associated with the user (e.g., the user's account with theentity issuing the VC). In this case, the issuer agent 412 may obtain anaccount identifier associated with the user from the request andidentify a DID based on a pre-stored mapping relationship between theaccount identifier and the DID. The issuer agent 412 may then create theunsigned VC based on the identified DID. The issuer agent 412 may alsocalculate a hash value of the content of the unsigned VC.

In some embodiments, the issuer agent 412 may obtain, in response toreceiving the request, a digital signature associated with the issuer.In some embodiments, the digital signature may be obtained from the KMS323. The issuer agent 412 may determine a key alias associated with theissuer 531 at step 1408. At step 1410, the issuer agent 412 may send arequest to the KMS 323 for a digital signature associated with theissuer 531 on the VC. The request may comprise the key alias, which maybe used for identification of the cryptographic keys associated with theissuer 531. The request may also comprise the hash value of the unsignedVC created by the issuer agent 412. The KMS 323 may store a plurality ofpublic-private key pairs in association with key aliases for entities orusers. Based on the key alias received from the issuer agent 412, theKMS 323 may identify the public-private key pair associated with theissuer 531. In some embodiments, the KMS 323 may store the public keyand an encrypted version of the private key. It may send the encryptedprivate key to a TEE associated with the KMS 323 for decryption. Theprivate key may then be used to create a digital signature of the issueron the VC. The digital signature may be created by encrypting the hashvalue of the unsigned VC using the private key. At step 1412, thedigital signature may be sent back to the issuer agent 412. Then, theissuer agent 412 may combine the unsigned VC with the digital signatureto compose a signed VC at step 1414. In this manner, the signed VC isgenerated based on the request received from the issuer 531 and thedigital signature.

In some embodiments, the issuer agent 412 may upload the VC to a serviceendpoint associated with the DID of the user or the holder of the VC.The issuer agent 412 may identify the service endpoint based on the DIDdocument associated with the DID. At step 1416, the issuer agent 412 maysend a query to a resolver 322 for the DID document associated with theDID for which the VC is issued. At step 1418, the resolver 322 mayformulate a transaction invoking a blockchain contract 331 for managingDIDs and send the transaction to one or more blockchain nodes associatedwith the blockchain 330 for execution. The transaction may compriseinformation associated with the DID and may be for retrieving a DIDdocument corresponding to the DID. As a result, the resolver 322 mayobtain the DID document corresponding to the DID at step 1420 andforward it to the SDK 312 at step 1422. Based on the DID document, theissuer agent 412 may obtain information (e.g., a network address)associated with a service endpoint (e.g., a VC repository 414) for theDID from the DID document. At step 1424, the issuer agent 412 may uploadthe VC to the service endpoint.

In some embodiments, the issuer agent 412 may store a status of the VC.The status of the VC may be stored in a blockchain 330. In someembodiments, the blockchain 330 may be used by a service endpointassociated with the issuer 531 of the VC. At step 1426, the issuer agent412 may send a status (e.g., valid, invalid) of the VC and a hash valueof the VC to the resolver 322 for storing in the blockchain 330. At step1428, the resolver 322 may generate and send to a blockchain node of theblockchain 330 associated with the service endpoint, a blockchaintransaction for adding information associated with the VC to theblockchain. The information may comprise the status and the hash valueof the VC. In some embodiments, the blockchain transaction may invoke ablockchain contract 331 for managing VCs. After sending the transactionto the blockchain node, the resolver 322 may determine that the hashvalue and status of the VC have been successfully stored at step 1430and may send a confirmation to the issuer agent 412 at step 1432. Insome embodiments, the status of the VC may also be stored locally. Atstep 1434, the issuer agent 412 may store the VC and its status at adatabase 416. The issuer agent 412 may receive a confirmation ofsuccessful storage at step 1436, send a confirmation to the agentservice API 410 at step 1438, which may then send a confirmation to theissuer 531 indicating that the VC has been successfully created at step1440. The confirmation to the issue may comprise the VC that has beencreated.

In some embodiments, the VC may be provided to the user or the holder ofthe VC. At step 1442, the issuer agent 412 may send the VC and/or astatus of the VC to an agent service API 410 associated with a useragent 411 for the holder of the VC. The agent service API 410 may callthe user agent 411 to upload the VC at step 1444. Here, the user agent411 may serve as a service endpoint for the DID of the holder of the VC.The user agent 411 may be implemented on the same physical system as theissuer agent 412. The user agent 411 may save the VC to a database 416at step 1446. After successful saving of the VC, the database 416 mayreturn a success confirmation to the user agent 411 at step 1448. Theuser agent 411 may send a confirmation to the agent service API 410 atstep 1450, which may forward a confirmation to the issuer agent 412 atstep 1452.

FIG. 15 illustrates a method for verifying a verifiable claim using anagent service in accordance with some embodiments. The operations of themethod presented below are intended to be illustrative. Depending on theimplementation, the method may include additional, fewer, or alternativesteps performed in various orders or in parallel. In some embodiments, aholder of a VC (or a subject of the VC) may present to a first entity(e.g., verifier) a VC issued by a second entity (e.g., issuer of theVC). The verifier may verify the VC with the aid of agent services 321.

In some embodiments, an agent service API 410 may receive from averifier 532 a request to verify a VC at step 1502. The VC may comprisea digital signature associated with an issuer of the VC. At step 1504,the agent service API 410 may call a function of the verifier agent 413for verifying the VC. In some embodiments, the verifier 532 may havedirectly obtained the VC from the holder of the VC. Alternatively, theverifier 532 may only have received an account identifier associatedwith a subject of the VC. The verifier 532 may obtain the VC byobtaining a DID associated with the subject of the VC based on apre-stored mapping relationship between the account identifier and theDID, obtaining a DID document associated with the DID, obtaininginformation associated with a service endpoint for managing VCs from theDID document, and obtaining the VC from the service endpoint.

In some embodiments, the verifier agent 413 may verify a status of theVC. The verifier agent 413 may obtain and verify the status using eithersteps 1506 a, 1508 a, 1510 a, and 1512 a or steps 1506 b, 1508 b, 1510b, and 1512 b. In some embodiments, the verifier agent 413 may obtainthe status of the VC from a blockchain storing information associatedwith a plurality of VCs. At step 1506 a, the verifier agent 413 may sendto a resolver 322 a query for a status of the VC. The query may comprisean identifier of the VC. At step 1508 a, the resolver 322 may create ablockchain transaction for retrieving a hash value and a status of theVC and send it to one or more blockchain nodes associated with ablockchain 300. The blockchain transaction may comprise a DID of thesubject of the VC and may invoke a blockchain contract 331 for managingVCs. At step 1510 a, the resolver 322 may obtain a status of the VC aswell as a hash value associated with the VC from the blockchain 330. Theresolver 322 may then send the hash value and status to the verifieragent 413 at step 1512 a for verification. The verifier agent 413 maycalculate a hash value by applying a hash function on the VC that wasprovided by the holder. The verifier agent 413 may authenticate thereceived status of the VC by comparing the hash value received from theblockchain 330 with the calculated hash value. If they are identical,the verifier agent 413 may determine that the received status doescorrespond to the VC. If the status indicates that the VC is valid, theverifier agent 413 may complete this step of the verification.

In some embodiments, the verifier agent 413 may obtain the status of theVC from a service endpoint associated with the VC. In some embodiments,the service endpoint may correspond to an issuer agent 412 associatedwith the issuer. At step 1506 b, the verifier agent 413 may send a queryto the issuer agent 412 for status of the VC. The issuer agent 412 mayquery the database 416 for the status of the VC at step 1508 b andobtain a status and a corresponding hash value of the VC at step 1510 b.The issuer agent 412 may send the hash value and the status to theverifier agent 413 at step 1512 b. The verifier agent 413 mayauthenticate the status and verify that the VC is valid in the mannerdiscussed above.

In some embodiments, the verifier agent 413 may determine that the VC isissued by the issuer identified on the VC. The verifier agent 413 mayobtain, based on the VC, a public key associated with the issuer. Theverifier agent 413 may identify the issuer based on an identifier in theVC. In some embodiments, the identifier may comprise a DID of theissuer. The public key may be obtained from the blockchain 330 based onthe DID of the issuer. At step 1514, the verifier agent 413 may send arequest to the resolver 322 for the public key associated with theissuer. The request may comprise the DID of the issuer. At step 1516,the resolver 322 may create a blockchain transaction invoking ablockchain contract 331 for retrieving a public key or a DID documentbased on a DID and send the blockchain transaction to a blockchain nodeof the blockchain 330. The resolver 322 may obtain the public key (e.g.,by retrieving from the DID document) at step 1518 and forward the publickey to the verifier agent 413 at step 1520. Then, at step 1522, theverifier agent 413 may verify the VC using the public key by determiningthat the digital signature is created based on a private key associatedwith the public key. In some embodiments, the verifier agent 413 mayverify one or more other facts about the VC. For example, the verifieragent 413 may obtain, from the VC, an issuance date of the VC andvalidate the obtained issuance date based on a comparison between theobtained issuance date and a current date. As another example, theverifier agent 413 may obtain, from the VC, an expiration date of the VCand validate that the VC has not expired based on the expiration dateand a current date. If verification of the VC is successful, theverifier agent may send a confirmation to the agent service API 410 atstep 1524. The agent service API 410 may send a message to the verifier532 confirming that the VC is verified at step 1526.

FIG. 16 illustrates a method for blockchain-based notification inaccordance with some embodiments. The operations of the method presentedbelow are intended to be illustrative. Depending on the implementation,the method may include additional, fewer, or alternative steps performedin various orders or in parallel.

In some embodiments, event data associated with one or more DIDs may bestored on a blockchain 330. The resolver 322 may obtain the event dataassociated with the one or more DIDs from the blockchain 330 to provideto one or more other systems. At step 1602, the resolver 322 may obtainthe event data associated with the one or more DIDs from the blockchain330. In some embodiments, the resolver 322 may send a synchronizationtask to a listener 424 to start the process of obtaining event data fromthe blockchain 330. The listener 424 may query data stored in theblockchain 330 for such event data. In some embodiments, the listener424 may send, to one or more blockchain nodes associated with theblockchain 330 for execution, one or more blockchain transactions forobtaining the event data. The blockchain transactions may include theone or more DIDs. The blockchain transactions may invoke one or moreblockchain contracts configured to manage correspondence relationshipsbetween the DIDs and various events in the blockchain. After obtainingthe event data, the listener 424 may update a database 423 based on theobtained event data. The event data may be associated with a verifiableclaim. A representation (e.g., hash value) of the verifiable claim isstored in the blockchain. In one embodiment, the event data associatedwith a DID may include one or more of the following: a registration ofthe DID in the blockchain (e.g., a successful or failed registration ofthe DID), an update to a DID document associated with the DID in theblockchain (e.g., a successful or failed addition of data to the DIDdocument), an issuance of a verifiable claim associated with the DID(e.g., a successful or failed issuance of a verifiable claim for the DIDwith the DID corresponding to an issuer or a subject of the verifiableclaim), etc. Detailed descriptions of DID and registration, DID documentand update, verifiable claims and issuance, issuer, and subject may bereferred to descriptions herein.

In some embodiments, the resolver 322 may generate one or morenotifications based on the obtained event data. For example, anotification for a successful DID registration may include a successmessage, a registered DID, etc. For another example, a notification fora successful DID document data addition may include a corresponding DID,an updated DID document, etc.

In some embodiments, at step 1604, the resolver 322 may place the one ormore generated notifications in a message queue 1601 for one or morecomputing devices to obtain the one or more notifications. The messagequeue 1601 may be stored in the database 452. The message queue 1601 maybe supported by a messenger 325 (also referred to as message broker orqueue messenger platform or service). For example, a messenger 325 mayconnect to the message queue 1601 to obtain the one or morenotifications from the message queue 1601.

In some embodiments, at step 1606, the messenger 325 may obtain aplurality of notifications from one or more message queues such as themessage queue 1601. In some embodiments, after obtaining the pluralityof notifications, at step 1608, the messenger 325 may filter theplurality of notifications to remove one or more unauthorizednotifications. For example, if DID xyz is unrelated to DID 123 (e.g.,neither a controller, nor a creator), the filtering process may removenotifications that are related to DID 123 and are associated with DIDxyz due to lack of authorization. Conversely, if DID abc is a controllerof DID 123, notifications that are related to DID 123 and are associatedwith DID abc will be stored for search and retrieval. When DID abcqueries, notifications related to DID abc as well as the notificationsthat are related to DID 123 and are associated with DID abc may beavailable for DID abc. Thus, unauthorized notifications may be filteredand not stored in a data store 1603. The data store 1603 may correspondto the memory 451.

In some embodiments, after obtaining the plurality of notifications, atstep 1608, the messenger 325 may categorize the plurality ofnotifications based on one or more of the following notificationparameters: event type (e.g., DID registration, DID document update,verifiable claim issuance), DID, DID creator (e.g., a DID of an entitythat created the DID of interest on behalf of the DID's owner), DIDcontroller (e.g., a DID of an entity entrusted to manage the DID ofinterest for the DID's owner), notification recipient (e.g., arecipient's DID of an intended recipient of the notification),verifiable claim issuer (e.g., a DID of an issuer of a verifiableclaim), verifiable claim subject (e.g., a DID of a subject of averifiable claim), etc. Categorizing the notifications may facilitateretrieval of the notifications in response to queries.

In some embodiments, at step 1610, the messenger 325 may store theobtained plurality of notifications in a data store 1603 in associationwith information of corresponding DIDs, corresponding blockchain heightsin the blockchain, etc. For example, for a DID document data updateevent, the messenger 325 may store a DID (e.g., owner DID, controllerDID, creator DID, etc.) corresponding to the DID document that wasupdated, the updated DID document (or the updated portion of the DIDdocument), and a blockchain height of a block storing the blockchaintransaction corresponding to the update event or the blockchaintransaction that triggered the update to the DID document. Thus, allnotifications related to a certain DID with the certain DID being a DIDowner, a creator for another DID, and/or a controller of another DID canbe obtained, categorically sorted, and stored. At step 1612, themessenger 325 may obtain a storage result for storing the obtainedplurality of notifications.

In some embodiments, at step 1614, the messenger 325 may obtain, from acomputing device (e.g., the user-side system 310) associated with afirst DID, a query about event data. The messenger 325 may forward thefirst DID to the agent 321 for verification. If the verificationsucceeds, the following steps may proceed. Otherwise, the followingsteps may not be performed. In response to the obtained query, at step1616, the messenger 325 may search a data store to obtain one or morenotifications for event data associated with the first DID and/or withone or more other DIDs. The one or more other DIDs may include, forexample, a second DID. The first and second DIDs are stored in theblockchain. That is, the messenger 325 may search for event datadirectly related to the first DID of the inquiring entity and/or eventdata related to the second DID that the first DID is authorized toobtain. For example, a DID document associated with the second DID mayinclude the first DID (e.g., under a parameter described below), and theDID document is stored in the blockchain 330.

In one embodiment, the DID document may include a parameter indicating acreator of the second DID, and the parameter may include the first DIDas the creator of the second DID. In one embodiment, the DID documentmay include a parameter indicating a controller of the second DID, andthe parameter may include the first DID as the controller of the secondDID. For example, a business employer with an employer DID (as anexample of the first DID) may apply for employee DIDs (as an example ofthe second DIDs) on behalf of its employees. Thus, a DID document of anemployee DID may include the employer DID under the creator parameter.Further, the employer may be authorized to manage the employee DIDs forits employees. Thus, the DID document of the employee DID may alsoinclude the employer DID under the controller parameter. If the employeefurther authorizes a third-party company to manage the employee DID, thethird-party company's DID may be added under the controller parameter orreplace the employer DID under the controller parameter.

In some embodiments, a current height H of the blockchain is based on anumber of blocks in the blockchain. For example, if the blockchaincurrently has 2000 blocks, the current height H may be 2000 (if countingfrom block 1, block 2, ... block 2000). In one embodiment, theblockchain height may refer to a block height of the latest block, whichis the sequence number of the latest block in the chain of blocks. Forexample, if the last block in the blockchain is the 2000th block, theblock height of the latest block may be 2000. Although the examples ofblockchain height and block height shown here start from block 1, it canbe appreciated that the first block can start from any sequence number.In one embodiments, if a current search is conducted among blockchaintransactions stored from block 1990 to block 2000 of a blockchaincurrently having 2000 blocks, the search may be referred to as conductedfrom a current starting height of 1990 to a current ending height of2000.

In some embodiments, to search the data store to obtain the one or morenotifications for the event data associated with the second DID, themessenger 325 may search the data store based on a current startingheight of the blockchain to obtain the one or more notifications for theevent data associated with the second DID. Additionally oralternatively, searches may be conducted to obtain notifications forevent data directly associated with the first DID or with other DIDs forwhich the first DID acts as a controller or creator. In one embodiment,the query obtained at step 1614 may include the current starting heightof the blockchain. The messenger 325 may search from the currentstarting height of the blockchain to a current ending height of theblockchain for the one or more notifications associated with the eventdata. Here, since the event data stored in the data store 1603 mayinclude associated blockchain heights as stored in the blockchain, themessenger 325 may search the data store 1603 based on the blockchainheights. Further, the messenger 325 may provide the current endingheight of the blockchain (e.g., at step 1618) for one or more of thefollowing: the computing device associated with the first DID (e.g., theuser-side system 310), another computing device associated with thesecond DID (e.g., a computing device of the owner of the second DID),etc.

In some embodiments, the current starting height may or may not be aprevious ending height provided from a previous search. For example, ifthe previous search ended at notifications associated with event datastored in block 999 of the blockchain. The next search (current search)may start from notifications associated with event data stored in block1000, or backtrack to notifications associated with event data stored inblock 990. In one embodiment, the query includes the current startingheight of the blockchain, and the current starting height of theblockchain is a previous ending height of the blockchain of a previoussearch. For example, if the notifications provided from the previoussearch were properly obtained and stored by the recipient. The currentstarting height provided in the query may be the same as the previousending height to continue obtaining notifications stored in unsearchedblocks (e.g., newly added blocks) of the blockchain. In one embodiment,the current starting height of the blockchain may include an offset froma previous ending height of the blockchain of a previous search. Forexample, if for some reason (e.g., system downtime or memory loss) thenotifications provided from the previous search were not properlyobtained or stored by the recipient, the recipient may backtrack thecurrent starting height from the previous ending height to recovernotifications lost from the previous search. Optionally, the currentsearch may extend beyond the previous ending height. Thus, thenotification recipients are provided with control over the startinglocation for each search, ensuring consistency of the notificationsobtained from the messenger over multiple rounds of queries andsearches. Alternatively, the recipient may fast-forward from theprevious ending height and skip some blocks to obtain the currentstarting height for query, thus skipping notifications corresponding toblockchain transactions stored in the skipped blocks.

In some embodiments, at step 1620, the messenger 325 may provide the oneor more notifications for the computing device associated with the firstDID (e.g., the user-side system 310). The computing device may subscribeto the notifications. In one embodiment, the messenger 325 may send thenotifications to the user-side system 310. In one embodiment, theuser-side system 310 may obtain the notifications from the messenger325. Overall, based on the parameters in the DID document, a creator mayeffectively obtain notifications for user accounts that it created forthe users, and a controller may effectively obtain notifications foruser accounts under its control. Creator and controller delegations forreceiving notification are thus enable, while preserving security innotification delivery.

In some embodiments, the above description for FIG. 16 may be referredto as a pull mode. Alternatively, a push mode may be used to pushnotifications from the messenger 325 to the user-side system 310. Insome embodiments, under the push mode, the step 1614 may be removedwhile keeping other steps, and the messenger 325 may send thenotifications to the user-side system 310 without having to obtain thequery first.

FIG. 17 illustrates a flowchart of a method for blockchain-basednotification in accordance with some embodiments. The method 1700 may beperformed by a device, apparatus, or system for blockchain-basednotification. The method 1700 may be performed by one or more componentsof the environment or system illustrated by FIGS. 1-5, such as one ormore components of the messenger 325. Depending on the implementation,the method 1700 may include additional, fewer, or alternative stepsperformed in various orders or in parallel.

Block 1710 includes obtaining, from a computing device associated with afirst decentralized identifier (DID), a query about event data.

In some embodiments, before obtaining the query, the method furthercomprises: obtaining a plurality of notifications from one or moremessage queues; and storing the plurality of notifications in the datastore in association with information of corresponding DIDs andcorresponding blockchain heights in the blockchain, wherein theplurality of notifications comprise the one or more notifications forthe event data associated with the second DID. In some embodiments,after obtaining the plurality of notifications, the method furthercomprises: filtering the plurality of notifications to remove one ormore unauthorized notifications. In some embodiments, after obtainingthe plurality of notifications, the method further comprises:categorizing the plurality of notifications based on one or more of thefollowing notification parameters: event type, DID, DID creator, DIDcontroller, notification recipient, verifiable claim issuer, andverifiable claim subject.

Block 1720 includes, in response to the obtained query, searching a datastore to obtain one or more notifications for event data associated witha second DID, wherein a DID document associated with the second DIDcomprises the first DID, and wherein the DID document is stored in ablockchain. In some embodiments, the DID document comprises a parameterindicating a creator of the second DID; and the parameter comprises thefirst DID as the creator of the second DID. In some embodiments, the DIDdocument comprises a parameter indicating a controller of the secondDID; and the parameter comprises the first DID as the controller of thesecond DID.

In some embodiments, the event data is associated with a verifiableclaim; and a representation of the verifiable claim, the first DID, andthe second DID are stored in the blockchain.

In some embodiments, the event data associated with the second DIDcomprises one or more of the following: a registration of the second DIDin the blockchain; an update to the DID document in the blockchain; anissuance of a first verifiable claim associated with the second DID,wherein the second DID corresponds to an issuer of the first verifiableclaim; and an issuance of a second verifiable claim associated with thesecond DID, wherein the second DID corresponds to a subject of thesecond verifiable claim.

In some embodiments, searching the data store to obtain the one or morenotifications for the event data associated with the second DIDcomprises: searching the data store based on a current starting heightof the blockchain to obtain the one or more notifications for the eventdata associated with the second DID. In some embodiments, searching thedata store based on the current starting height of the blockchain toobtain the one or more notifications for the event data associated withthe second DID comprises: searching from the current starting height ofthe blockchain to a current ending height of the blockchain for the oneor more notifications associated with the event data; and the methodfurther comprises providing the current ending height of the blockchainfor one or more of the following: the computing device associated withthe first DID and another computing device associated with the secondDID.

In some embodiments, the query comprises the current starting height ofthe blockchain; and the current starting height of the blockchaincomprises an offset from a previous ending height of the blockchain of aprevious search. In some embodiments, the query comprises the currentstarting height of the blockchain; and the current starting height ofthe blockchain is a previous ending height of the blockchain of aprevious search.

Block 1730 includes providing the one or more notifications for thecomputing device associated with the first DID.

FIG. 18 illustrates a block diagram of a computer system forblockchain-based notification in accordance with some embodiments. Thesystem 1800 may be an example of an implementation of one or morecomponents of the service-side system 320 of FIG. 3 or one or more othercomponents illustrated in FIGS. 1-5 such as the messenger 325. Themethod 1700 may be implemented by the computer system 1800. The computersystem 1800 may comprise one or more processors and one or morenon-transitory computer-readable storage media (e.g., one or morememories) coupled to the one or more processors and configured withinstructions executable by the one or more processors to cause thesystem or device (e.g., the processor) to perform the above-describedmethod, e.g., the method 1700. The computer system 1800 may comprisevarious units/modules corresponding to the instructions (e.g., softwareinstructions). In some embodiments, the computer system 1800 may bereferred to as an apparatus for blockchain-based notification. Theapparatus may comprise an obtaining module 1810 for obtaining, from acomputing device associated with a first decentralized identifier (DID),a query about event data; a searching module 1820 for, in response tothe obtained query, searching a data store to obtain one or morenotifications for event data associated with a second DID, wherein a DIDdocument associated with the second DID comprises the first DID, andwherein the DID document is stored in a blockchain; and a providingmodule 1830 for providing the one or more notifications for thecomputing device associated with the first DID.

The techniques described herein may be implemented by one or morespecial-purpose computing devices. The special-purpose computing devicesmay be desktop computer systems, server computer systems, portablecomputer systems, handheld devices, networking devices or any otherdevice or combination of devices that incorporate hard-wired and/orprogram logic to implement the techniques. The special-purpose computingdevices may be implemented as personal computers, laptops, cellularphones, camera phones, smart phones, personal digital assistants, mediaplayers, navigation devices, email devices, game consoles, tabletcomputers, wearable devices, or a combination thereof. Computingdevice(s) may be generally controlled and coordinated by operatingsystem software. Conventional operating systems control and schedulecomputer processes for execution, perform memory management, providefile system, networking, I/O services, and provide a user interfacefunctionality, such as a graphical user interface (“GUI”), among otherthings. The various systems, apparatuses, storage media, modules, andunits described herein may be implemented in the special-purposecomputing devices, or one or more computing chips of the one or morespecial-purpose computing devices. In some embodiments, the instructionsdescribed herein may be implemented in a virtual machine on thespecial-purpose computing device. When executed, the instructions maycause the special-purpose computing device to perform various methodsdescribed herein. The virtual machine may include a software, hardware,or a combination thereof

FIG. 19 illustrates a block diagram of a computer system in which any ofthe embodiments described herein may be implemented. The system 1900 maybe implemented in any of the components of the environments or systemsillustrated in FIGS. 1-5. The software applications or servicesillustrated in FIGS. 1-5 may be implemented and operated on the system1900. One or more of the example methods illustrated by FIGS. 6-16 maybe performed by one or more implementations of the computer system 1900.

The computer system 1900 may include a bus 1902 or other communicationmechanism for communicating information, one or more hardwareprocessor(s) 1904 coupled with bus 1902 for processing information.Hardware processor(s) 1904 may be, for example, one or more generalpurpose microprocessors.

The computer system 1900 may also include a main memory 1906, such as arandom access memory (RAM), cache and/or other dynamic storage devices,coupled to bus 1902 for storing information and instructions executableby processor(s) 1904. Main memory 1906 also may be used for storingtemporary variables or other intermediate information during executionof instructions executable by processor(s) 1904. Such instructions, whenstored in storage media accessible to processor(s) 1904, render computersystem 1900 into a special-purpose machine that is customized to performthe operations specified in the instructions. The computer system 1900may further include a read only memory (ROM) 1908 or other staticstorage device coupled to bus 1902 for storing static information andinstructions for processor(s) 1904. A storage device 1910, such as amagnetic disk, optical disk, or USB thumb drive (Flash drive), etc., maybe provided and coupled to bus 1902 for storing information andinstructions.

The computer system 1900 may implement the techniques described hereinusing customized hard-wired logic, one or more ASICs or FPGAs, firmwareand/or program logic which in combination with the computer systemcauses or programs computer system 1900 to be a special-purpose machine.According to one embodiment, the operations, methods, and processesdescribed herein are performed by computer system 1900 in response toprocessor(s) 1904 executing one or more sequences of one or moreinstructions contained in main memory 1906. Such instructions may beread into main memory 1906 from another storage medium, such as storagedevice 1910. Execution of the sequences of instructions contained inmain memory 1906 may cause processor(s) 1904 to perform the processsteps described herein. In alternative embodiments, hard-wired circuitrymay be used in place of or in combination with software instructions.

The main memory 1906, the ROM 1908, and/or the storage device 1910 mayinclude non-transitory storage media. The term “non-transitory media,”and similar terms, as used herein refers to media that store data and/orinstructions that cause a machine to operate in a specific fashion, themedia excludes transitory signals. Such non-transitory media maycomprise non-volatile media and/or volatile media. Non-volatile mediaincludes, for example, optical or magnetic disks, such as storage device1910. Volatile media includes dynamic memory, such as main memory 1906.Common forms of non-transitory media include, for example, a floppydisk, a flexible disk, hard disk, solid state drive, magnetic tape, orany other magnetic data storage medium, a CD-ROM, any other optical datastorage medium, any physical medium with patterns of holes, a RAM, aPROM, and EPROM, a FLASH-EPROM, NVRAM, any other memory chip orcartridge, and networked versions of the same.

The computer system 1900 may include a network interface 1918 coupled tobus 1902. Network interface 1918 may provide a two-way datacommunication coupling to one or more network links that are connectedto one or more local networks. For example, network interface 1918 maybe an integrated services digital network (ISDN) card, cable modem,satellite modem, or a modem to provide a data communication connectionto a corresponding type of telephone line. As another example, networkinterface 1918 may be a local area network (LAN) card to provide a datacommunication connection to a compatible LAN (or WAN component tocommunicate with a WAN). Wireless links may also be implemented. In anysuch implementation, network interface 1918 may send and receiveelectrical, electromagnetic or optical signals that carry digital datastreams representing various types of information.

The computer system 1900 can send messages and receive data, includingprogram code, through the network(s), network link and network interface1918. In the Internet example, a server might transmit a requested codefor an application program through the Internet, the ISP, the localnetwork and the network interface 1918.

The received code may be executed by processor(s) 1904 as it isreceived, and/or stored in storage device 1910, or other non-volatilestorage for later execution.

Each of the processes, methods, and algorithms described in thepreceding sections may be embodied in, and fully or partially automatedby, code modules executed by one or more computer systems or computerprocessors comprising computer hardware. The processes and algorithmsmay be implemented partially or wholly in application-specificcircuitry.

The various features and processes described above may be usedindependently of one another or may be combined in various ways. Allpossible combinations and sub-combinations are intended to fall withinthe scope of this specification. In addition, certain method or processblocks may be omitted in some implementations. The methods and processesdescribed herein are also not limited to any particular sequence, andthe blocks or states relating thereto can be performed in othersequences that are appropriate. For example, described blocks or statesmay be performed in an order other than that specifically disclosed, ormultiple blocks or states may be combined in a single block or state.The examples of blocks or states may be performed in serial, inparallel, or in some other manner. Blocks or states may be added to orremoved from the disclosed embodiments. The examples of systems andcomponents described herein may be configured differently thandescribed. For example, elements may be added to, removed from, orrearranged compared to the disclosed embodiments.

The various operations of methods described herein may be performed, atleast partially, by one or more processors that are temporarilyconfigured (e.g., by software) or permanently configured to perform therelevant operations. Whether temporarily or permanently configured, suchprocessors may constitute processor-implemented engines that operate toperform one or more operations or functions described herein.

Similarly, the methods described herein may be at least partiallyprocessor-implemented, with a particular processor or processors beingan example of hardware. For example, at least some of the operations ofa method may be performed by one or more processors orprocessor-implemented engines. Moreover, the one or more processors mayalso operate to support performance of the relevant operations in a“cloud computing” environment or as a “software as a service” (SaaS).For example, at least some of the operations may be performed by a groupof computers (as examples of machines including processors), with theseoperations being accessible via a network (e.g., the Internet) and viaone or more appropriate interfaces (e.g., an Application ProgramInterface (API)).

The performance of certain of the operations may be distributed amongthe processors, not only residing within a single machine, but deployedacross a number of machines. In some embodiments, the processors orprocessor-implemented engines may be located in a single geographiclocation (e.g., within a home environment, an office environment, or aserver farm). In other embodiments, the processors orprocessor-implemented engines may be distributed across a number ofgeographic locations.

Throughout this specification, plural instances may implementcomponents, operations, or structures described as a single instance.Although individual operations of one or more methods are illustratedand described as separate operations, one or more of the individualoperations may be performed concurrently, and nothing requires that theoperations be performed in the order illustrated. Structures andfunctionality presented as separate components in configurations may beimplemented as a combined structure or component. Similarly, structuresand functionality presented as a single component may be implemented asseparate components. These and other variations, modifications,additions, and improvements fall within the scope of the subject matterherein.

Although an overview of the subject matter has been described withreference to specific embodiments, various modifications and changes maybe made to these embodiments without departing from the broader scope ofembodiments of the specification. The Detailed Description should not tobe taken in a limiting sense, and the scope of various embodiments isdefined only by the appended claims, along with the full range ofequivalents to which such claims are entitled. Furthermore, relatedterms (such as “first,” “second,” “third,” etc.) used herein do notdenote any order, height, or importance, but rather are used todistinguish one element from another element. Furthermore, the terms“a,” “an,” and “plurality” do not denote a limitation of quantityherein, but rather denote the presence of at least one of the articlesmentioned. In addition, herein, “or” is inclusive and not exclusive,unless expressly indicated otherwise or indicated otherwise by context.Therefore, herein, “A or B” means “A, B, or both,” unless expresslyindicated otherwise or indicated otherwise by context. Moreover, “and”is both joint and several, unless expressly indicated otherwise orindicated otherwise by context. Therefore, herein, “A and B” means “Aand B, jointly or severally,” unless expressly indicated otherwise orindicated otherwise by context.

1. A computer-implemented method for blockchain-based notification,comprising: obtaining, from a computing device associated with a firstdecentralized identifier (DID), a query about event data; in response tothe obtained query, searching a data store to obtain one or morenotifications for event data associated with a second DID, wherein a DIDdocument associated with the second DID comprises the first DID, andwherein the DID document is stored in a blockchain; and providing theone or more notifications for the computing device associated with thefirst DID.
 2. The method of claim 1, wherein: the DID document comprisesa parameter indicating a creator of the second DID; and the parametercomprises the first DID.
 3. The method of claim 1, wherein: the DIDdocument comprises a parameter indicating a controller of the secondDID; and the parameter comprises the first DID.
 4. The method of claim1, wherein: the event data is associated with a verifiable claim; and arepresentation of the verifiable claim is stored in the blockchain. 5.The method of claim 1, wherein the event data associated with the secondDID comprises one or more of the following: a registration of the secondDID in the blockchain; an update to the DID document in the blockchain;an issuance of a first verifiable claim associated with the second DID,wherein the second DID corresponds to an issuer of the first verifiableclaim; and an issuance of a second verifiable claim associated with thesecond DID, wherein the second DID corresponds to a subject of thesecond verifiable claim.
 6. The method of claim 1, before obtaining thequery, further comprising: obtaining a plurality of notifications fromone or more message queues; and storing the plurality of notificationsin the data store in association with information of corresponding DIDsand corresponding blockchain heights in the blockchain, wherein theplurality of notifications comprise the one or more notifications forthe event data associated with the second DID.
 7. The method of claim 6,after obtaining the plurality of notifications, further comprising:filtering the plurality of notifications to remove one or moreunauthorized notifications.
 8. The method of claim 6, after obtainingthe plurality of notifications, further comprising: categorizing theplurality of notifications based on one or more of the followingnotification parameters: event type, DID, DID creator, DID controller,notification recipient, verifiable claim issuer, and verifiable claimsubject.
 9. The method of claim 1, wherein searching the data store toobtain the one or more notifications for the event data associated withthe second DID comprises: searching the data store based on a currentstarting height of the blockchain to obtain the one or morenotifications for the event data associated with the second DID.
 10. Themethod of claim 9, wherein: searching the data store based on thecurrent starting height of the blockchain to obtain the one or morenotifications for the event data associated with the second DIDcomprises: searching from the current starting height of the blockchainto a current ending height of the blockchain for the one or morenotifications associated with the event data; and the method furthercomprises providing the current ending height of the blockchain for oneor more of the following: the computing device associated with the firstDID and another computing device associated with the second DID.
 11. Themethod of claim 9, wherein: the query comprises the current startingheight of the blockchain; and the current starting height of theblockchain comprises an offset from a previous ending height of theblockchain of a previous search.
 12. The method of claim 9, wherein: thequery comprises the current starting height of the blockchain; and thecurrent starting height of the blockchain is a previous ending height ofthe blockchain of a previous search.
 13. A system for blockchain-basednotification, the system comprising one or more processors and one ormore non-transitory computer-readable memories coupled to the one ormore processors and configured with instructions executable by the oneor more processors to cause the system to perform operations comprising:obtaining, from a computing device associated with a first decentralizedidentifier (DID), a query about event data; in response to the obtainedquery, searching a data store to obtain one or more notifications forevent data associated with a second DID, wherein a DID documentassociated with the second DID comprises the first DID, and wherein theDID document is stored in a blockchain; and providing the one or morenotifications for the computing device associated with the first DID.14. The system of claim 13, wherein: the DID document comprises aparameter indicating a creator of the second DID; and the parametercomprises the first DID.
 15. The system of claim 13, wherein: the DIDdocument comprises a parameter indicating a controller of the secondDID; and the parameter comprises the first DID.
 16. The system of claim13, wherein: the event data is associated with a verifiable claim; and arepresentation of the verifiable claim is stored in the blockchain. 17.A non-transitory computer-readable storage medium for blockchain-basednotification, the storage medium configured with instructions executableby one or more processors to cause the one or more processors to performoperations comprising: obtaining, from a computing device associatedwith a first decentralized identifier (DID), a query about event data;in response to the obtained query, searching a data store to obtain oneor more notifications for event data associated with a second DID,wherein a DID document associated with the second DID comprises thefirst DID, and wherein the DID document is stored in a blockchain; andproviding the one or more notifications for the computing deviceassociated with the first DID.
 18. The storage medium of claim 17,wherein: the DID document comprises a parameter indicating a creator ofthe second DID; and the parameter comprises the first DID.
 19. Thestorage medium of claim 17, wherein: the DID document comprises aparameter indicating a controller of the second DID; and the parametercomprises the first DID.
 20. The storage medium of claim 17, wherein:the event data is associated with a verifiable claim; and arepresentation of the verifiable claim is stored in the blockchain.